Does mathematical sophistication play a role during paper review?
Mathematical sophistication and mathematical density are often confused for one another, and this confusion often extends to reviewers and the "customs" of scientific communities.  To my mind, the best mathematical presentation is the most lucid and simple, and it is certainly the case that important consequences often come from rather simple equations.  The simpler your equations, however, the more that the contribution of the paper will depend on your exploration of those consequences (theoretically or empirically), rather than the mathematics per se.

It can be very tempting to "puff up" the perceived complexity of your mathematics by adding notational complexity or other baroquery.  It may even work well when dealing with some communities (I know of some rather cynical and unfortunately successful experiments performed by certain colleagues of mine).  I would strongly advise, however, against doing so.  Write the paper as clearly and simply as possible, given the true nature of the mathematics within.  Doing so may incur negative judgement from those who confuse "simple" and "trivial," but to do otherwise is scientifically dishonest. Moreover, if your work has value, it will show in the consequences of the mathematics rather than its nature, and writing it more accessibly is likely, in the long run, to increase its impact.

Finally, note that this dictum goes the other way as well: when you are presenting a complex mathematical result to an audience that does not appreciate mathematical complexity, do not attempt to pretend the mathematics is not complex.  In this case, however, appendices and supplementary information is the way to go: keep only as much of key elements in the main text as is appropriate for the audience, and put the rest where those who are interested can readily find it without interrupting the flow of the main text.