Why don't the Big 5 personality traits have more neutral names? Lots of different areas of study appropriate common-language terms as jargon words with a specific meaning in the context of that particular field, but the names of the Big 5 personality traits have always bothered me. They appear to be rather prejudicial.

For example, scoring high on Agreeableness sounds like it should be a good thing to an uninformed person. But from a psychological perspective, highly agreeable people often allow themselves to be taken advantage of, and tend to be emotional doormats.

Openness is another one that is confusing. Nobody wants to believe they are closed-minded. But in reality, a person who scores low in Openness is consistent, cautious, and deliberate in their actions, which is not a bad thing at all in many circumstances.

Language has a tendency to bias our thinking in certain ways, and one would think this would be more of a problem in psychology than in other sciences.  Other sciences either borrow obscure words from other languages or they make up new ones to avoid terms that are culturally or linguistically loaded.

Since there is a growing body of evidence that the Big 5 are more innate than learned, and since each dimension is a scale on which either extreme is considered a bad thing, it would seem to me that we'd want to use less partisan names for those traits.

Why aren't the descriptors more neutral in tone?
Well, in a recent debate whether Big Five is... ahem... sexist, this was mentioned, which pertains your question:


  There’s another flaw when it comes to taking Big Five personality tests online. The online versions of the Big Five traits inform people of negative character traits, without explaining that the positivity or negativity of all characteristics is shaped by context.
  
  Costa believes that the Big Five’s willingness to point out negative traits makes the test more accurate: Myers-Briggs avoids “anything that could be negative. And that’s a great big marketing thing,” he says. But each potentially negative Big Five character trait is informed by the situation. “They’re only negative in certain contexts,” he says.
  
  For example, Costa explains, agreeable people are great for a blind date, but tend to be overly dependent. Disagreeable people, meanwhile, aren’t good at smoothing over arguments. But they’re also less likely to obediently follow immoral orders—such as those demonstrated by the Milgram experiment, wherein participants are asked to administer increasingly intense electric shocks to a victim. (The longer IPIP-NEO test briefly acknowledged the importance of context, noting, “agreeableness is not useful in situations that require tough or absolute objective decisions,” but the Big Five Inventory website offered no such explanations.)


For more context, Paul Costa is one the original authors of NEO-PI, one of the main instruments that shaped Big Five testing.

So, according to him, avoiding negativity either explicit (or the complementary/implicit one) in the design wasn't a goal because it hindered accuracy. I guess that doesn't completely answer the question about naming of the dimensions, but it's probably informative. (Do note that one of the Big 5 dimensions has a rather negative name--neuroticism.) 

Costa's point about commercial tests' negativity-avoidance seems to apply to DISC as well.



The factor-naming issue itself was covered in detail in a 1992 paper of McCrae and John (which has very high number of citations for a psychology paper):


  The consensus that five-factorists see among themselves may be puzzling to outsiders because the "disagreement among analysts as to factor titles" that Tupes and Christal noted still plagues the field (John,
  1990b). Factor names reflect historical accidents, conceptual positions,
  and the entrenchment that comes from a published body of literature
  and from published instruments. There are two prominent systems for
  naming the factors, one derived from the lexical tradition and one from
  the questionnaire tradition.
  
  Many writers take Norman's (1963) annunciation of an "adequate
  taxonomy of personality attributes" derived from Cattell's reduction of
  natural language trait terms as the formal beginning of the FFM, and
  the factor numbers and names Norman chose—I: Extraversion or Surgency; II: Agreeableness; III: Conscientiousness; IV: Emotional Stability;
  and V: Culture—are often used. Peabody and Goldberg (1989)
  have noted that the order in which these factors emerged roughly parallels
  their representation among English language trait terms in the
  dictionary: Many more words can be found to describe aspects of Factors
  I through III than of Factors IV and V. The factor numbers, I to V,
  are thus meaningful designations. Roman numerals also have the advantage
  of being theoretically neutral; they seem to stand above the fray
  of disputed factor interpretations.
  
  The second tradition that led to the modern FFM comes from the
  analysis of questionnaires, and particularly from the work of H. J.
  Eysenck, who identified Extraversion (E) and Neuroticism (N) as major
  components of psychological tests. (It was Wiggins, 1968, who dubbed
  these the "Big Two," setting the stage for Goldberg's 1981 designation
  of the FFM as the "Big Five.") Costa and McCrae (1980) added
  a dimension they called Openness to Experience (O), and later (1985,
  1989) created scales to measure Agreeableness (A) and Conscientiousness
  (C). A number of publications (e.g., Borkenau &amp; Ostendorf, 1990;
  Funder &amp; Colvin, 1988; Tellegen &amp; Waller, in press; Wiggins &amp; Pincus,
  1989; Zuckerman, Bernieri, Koestner, &amp; Rosenthal, 1989) have
  adopted this nomenclature. Note that N corresponds to low Emotional
  Stability, —IV, and O is a variant of Norman's Factor V.
  
  If the advantage of the Norman numbers is their theoretical neutrality,
  the disadvantage is their low mnemonic value. Initials, originally popularized
  by H. J. Eysenck, are easier to interpret, and they may be less
  theoretically laden than full names. To those for whom Neuroticism
  connotes psychiatric disorder, negative affectivity (Watson &amp; Clark,
  1984) or simply nervousness may seem more apt; all can be characterized
  by N. Likewise, E can also stand for energy or enthusiasm (cf.
  Watson &amp; Clark, in press); O for originality; A for affiliation (Leary,
  1957) or affection (Brand, 1984), and C for constraint (Tellegen, 1982)
  or control (Krug &amp; Johns, 1986).


So yes, if the spelled-out names really bother interpretation-wise, an alternative is to use just the first letter designator (and/or numbers, but the latter seems a less popular approach). I did see recent papers do the former (use just the letters) although mainly in tables for compactness.

And in excruciating detail as to level of consensus on the naming of each factor (which seems to be roughly N > E ~ A ~ C > O), the same paper continues:


  The problem of what to call the factors is not merely a matter of convention.
  The labels refiect conceptualizations, and five-factor advocates
  differ in the details of their views on the factors, and thus in their
  preferred names. [...]
  
  There is probably the least controversy about the definition of N. N
  represents individual differences in the tendency to experience distress,
  and in the cognitive and behavioral styles that follow from this tendency.
  High N scorers experience chronic negative affects (Watson &amp;
  Clark, 1984) and are prone to the development of a variety of psychiatric
  disorders (Zonderman, Stone, &amp; Costa, 1989). The recurrent
  nervous tension, depression, frustration, guilt, and self-consciousness
  that such individuals feel is often associated with irrational thinking,
  low self-esteem, poor control of impulses and cravings, somatic complaints,
  and ineffective coping (McCrae &amp; Costa, 1987). Individuals
  low in N are not necessarily high in positive mental health, however
  that may be defined—they are simply calm, relaxed, even-tempered,
  unflappable.
  
  Despite the long and common use of the term Extraversion, there is
  less consensus about E. Most of the differences can be traced to the
  fact that E and A together define the Interpersonal Circumplex, around
  which interpersonal terms are spaced almost evenly. The traditional
  axes of the circumplex are Dominance (or Status) and Affiliation (or
  Love; Wiggins, 1979), and the major dispute about E (Norman's Factor
  1) concerns its alignment with these axes. Goldberg (1990), guided
  by his analyses of English language trait terms, and Wiggins (in press),
  guided by the interpersonal tradition, identify this factor with Dominance.
  McCrae and Costa (1989c) argue that E is best seen as located
  midway between Dominance and Warmth (although perhaps a bit closer
  to Dominance). This position, which Peabody and Goldberg (1989)
  designate as I', is close to the location of such traditional questionnaire
  measures of E as H. J. Eysenck and S. B. G. Eysenck's (1975) E scale
  and the EI scale of the MBTI.
  
  The advantage ofthe I' position is that it aligns the factor more closely
  with its noninterpersonal aspects, particularly positive emotionality. As
  Watson and Clark describe in their contribution to this issue, the tendencies
  to experience positive and negative emotions are not opposites, but
  orthogonal dimensions that define an affective plane. People who are
  cheerful, enthusiastic, optimistic, and energetic are not necessarily low
  in anxiety or depression—that depends on their level of N. But cheerful
  people consistently tend to be dominant, talkative, sociable, and warm,
  and Watson and Clark (in press) argue that positive emotionality should
  be seen as the core of E. This somewhat unorthodox view is probably
  a useful corrective to the narrowly interpersonal interpretation of E as
  sociability.
  
  E is distinguished by its breadth of content. In their review, Watson
  and Clark (in press) identified seven components of E: venturesomeness,
  affiliation, positive affectivity, energy, ascendance, and ambition.
  As Table 1 shows, Costa and McCrae's view of E is similarly broad,
  although they would divide affiliation into warmth and gregariousness
  and assign ambition to C." The fact that such a wide variety of interpersonal,
  affective, and temperamental variables covary probably accounts
  for the fact that this factor is so well represented in English language
  adjectives and so often described by personality theorists.
  The lexical literature suggests that individuals low in E can be described
  as quiet, reserved, retiring, shy, silent, and withdrawn (John,
  1990a), and Q-sort correlates point to emotional blandness and overcontrol
  of impulses as additional attributes. Nowhere in this description
  is introspectiveness seen: Low E must be distinguished from Guilford's
  (1977) Thinking Introversion (which is more closely related to O and
  C). The confusion between social and thinking introversions is perpetuated
  in the MBTI, where both kinds of traits are attributed to individuals
  classified as Introverts. In fact, the MBTI EI scale is a relatively pure
  measure of low E (McCrae &amp; Costa, 1989a).
  
  The label Agreeableness has been almost universally used for Norman's
  Factor II, but as Digman (1990) noted, "Agreeableness . . .
  seems tepid for a dimension that appears to involve the more humane
  aspects of humanity—characteristics such as altruism, nurturance, caring,
  and emotional support at the one end of the dimension, and hos
  tility, indifference to others, self-centeredness, spitefulness, and jealousy
  at the other" (pp. 422-424). Digman and Takemoto-Chock (1981)
  offered "Friendly Compliance versus Hostile Noncompliance" as an
  alternative descriptor for the factor, and Graziano and Eisenberg (in
  press) adopted the contrast "Agreeableness versus Antagonism."
  Because A must be orthogonal to E, the location—and thus the interpretation—
  of A depends to some extent on one's view of E. Again,
  Goldberg and Wiggins see this factor as Love or Warmth; Costa et al.
  (1991) note a cluster of attributes that blend Warmth and Submission,
  including trust, modesty, and compliance.
  
  Like A, C is a highly evaluated dimension; indeed, A and C are
  the classic dimensions of character, describing "good" versus "evil"
  and "strong-willed" versus "weak-willed" individuals. Perhaps it was
  these moral overtones that often led scientific psychologists to ignore
  these factors, but in fact, both represent objectively observable dimensions
  of individual differences. Some people are thorough, neat, wellorganized,
  diligent, and achievement-oriented, whereas others are not,
  and self-reports of these characteristics can be validated by peer or
  spouse ratings (McCrae &amp; Costa, 1987).
  
  A number of different conceptions of C have been offered. Tellegen's
  (1982) Constraint and Hogan's (1986) Prudence reflect an inhibitive
  view of C as a dimension that holds impulsive behavior in check.
  Digman and Takemoto-Chock's (1981) Will to Achieve represents a
  proactive view of C as a dimension that organizes and directs behavior.
  The term Conscientiousness combines both aspects, because it can
  mean either governed by conscience or diligent and thorough. Empirically,
  both kinds of traits seem to covary.
  
  The greatest controversy concerns O, and the root ofthe controversy
  is the disparity between natural language and questionnaire studies.
  Studies of trait adjectives in English (Goldberg, 1990; John, 1990a)
  and German (Ostendorf, 1990) typically show a factor defined by such
  items as intelligent, imaginative, and perceptive, and researchers from
  Fiske (1949) to Hogan (1986) and Digman (1990) have identified this
  factor as some form of Intellect. However, many traits related to O
  are not represented among English trait adjectives—there is, for example,
  no single English word that means "sensitive to art and beauty"
  (McCrae, 1990). Researchers using questionnaires have typically found
  a much broader factor that includes, in addition to creativity and intellectual
  interests, differentiated emotions, aesthetic sensitivity, need for
  variety, and unconventional values. This broader concept can be traced
  to Rogers (1961), Rokeach (1960), and Coan (1974); McCrae and Costa
  (in press) have argued that O is seen structurally in the depth, scope,
  and permeability of consciousness, and motivationally in the need for
  variety and experience. Ideas, of course, form an important aspect of
  consciousness, but fantasies, feelings, sensations, and values are also
  experiences to which individuals can be more or less open.
  Several discussions of the relative merits of these two conceptions
  have been offered (Digman, 1990; John, 1990a; McCrae &amp; Costa,
  1985b, in press; Peabody &amp; Goldberg, 1989). One point that should
  be emphasized is that neither Openness nor Intellect is equivalent to
  measured intelligence; O is a dimension of personality, not intellectual
  ability, and many people score high in O without having a correspondingly
  high IQ.
  
  A recent study illustrates the empirical basis for broadening the conception
  of this factor beyond Intellect. John (1989a) examined ACL
  and CQS data from expert raters at the Institute of Personality Assessment
  and Research. Based on a review of the literature, a panel of
  judges selected 112 prototype items from the ACL to mark the five dimensions.
  Many of the terms selected to represent O were consistent
  with either an Intellect or an Openness interpretation, including wide
  interests, imaginative, original, curious, and artistic. But because the
  literature emphasized the Intellect interpretation, judges also included
  such terms as wise, logical, and foresighted. When observer ratings on
  the 112 items were factored for a sample of 280 ratees, the five-factor
  model was clearly recovered, but wise, logical, and foresighted were
  not among the clear definers of the Intellect/Openness factor (Table 1
  lists the six highest-loading adjectives). Empirical analyses shifted the
  factor from a clear Intellect to a mixed Intellect/Openness factor.
  When ACL factor scores were correlated with CQS ratings by the
  same experts, the significant correlates (|r | > .40) showed the full range
  of traits associated with Openness. Individuals rated low on the factor
  were described by "judges in conventional terms," "favors conservative
  values," and "represses anxiety;" those rated high were described by
  "high degree of intellectual capacity," "enjoys aesthetic impressions,"
  "has wide interests," and "unusual, unconventional thought." As seen
  in this list, O includes aspects of intellect, but is considerably broader
  in scope.


What is obvious from all this is that many researchers have gone to great lengths to put interpretive names to the factors. You can argue that that is a bad thing, but then I'm not here to argue the counterpoint, but to show it happened.

There are however some researchers which have argued that [counter]point, on the basis that interpretive naming can lead to further testable hypotheses as to the underlying mechanisms for the factors:


  Whatever
  the inadequacies of the natural language for
  scientific systematics, broad dimensions inferred
  from folk usage are not a bad place
  to start a taxonomy. Even in the biological
  taxonomy of animals, “the technical system
  evolved from the vernacular” (Simpson,
  1961, pp. 12–13).
  
  Obviously, a system that initially derives
  from the natural language does not need to
  reify such terms indefinitely. Indeed, several of
  the dimensions included among the Big Five,
  most notably Extraversion and Neuroticism,
  have been the target of various physiological
  and mechanistic explanations (e.g., Canli et
  al., 2001; see also L. A. Clark, 2005). In research
  on emotion regulatory processes, the
  links between the Big Five, the chronic use
  of particular regulatory strategies, and their
  emotional and social consequences are being
  articulated (John &amp; Gross, 2007). Similarly,
  the conceptual explication of Extraversion
  and Neuroticism as persistent dispositions
  toward thinking and behaving in ways that
  foster, respectively, positive and negative affective
  experiences (e.g., Tellegen, 1985; see
  also Clark &amp; Watson, Chapter 9, this volume)
  promises to connect the Big Five with
  individual differences in affective functioning,
  which, in turn, may be studied in more tightly
  controlled laboratory settings (see Gross,
  Chapter 28, this volume). At this point, the
  Big Five differentiate domains of individual
  differences that have similar surface manifestations—
  just like the early animal taxonomy
  that was transformed by better accounts of
  evolutionary processes and by the advent of
  new tools, such as molecular genetics. Likewise,
  the structures and processes underlying
  these personality trait domains are now
  beginning to be explicated. Explanatory and mechanistic terms will likely change the definition
  and assessment of the Big Five dimensions
  as we know them today.