Is zazen practised for its own sake, or as a means to end suffering? Experts seem to say different things
Actually, the answer is very simple: meditation is practiced to achieve tathata (suchness), which is a state of realization of the Third Noble Truth. Because tathata involves cessation of aversion to any "this" and of longing for any "that", its attainment requires a mindset without a goal. It would be more precise to say that no-goal is a method of meditation, but that would risk leaving some subtle shadow of goal in practitioner's mind, hence the official statement that meditation has no goal. Because Buddhism aims at liberation from (among other things) deep-lying stereotypes/assumptions and implicit conceptual boundaries it necessarily involves tricks like this. Another corollary of the above, is that it's never enough to reason about these things intellectually, one needs to take them on as actual frame of reference for them to have an experiential effect.

This point is well illustrated by Dutiya Anuruddha Sutta (AN 3.128 or 3.130 or 131 depending how you count) -- the below amateurish translation is mine but here is another one.


  Then venerable Anuruddha came to venerable Shariputra and
  said:
  
  -- As much as I, friend Shariputra, try and look at things with purified Heavenly Eye, try and see things with thousandfold-superhuman
  vision, train in confidence unmovable, in awareness undimmable, in
  tranquillity imperturbable, and in focused mind unscattered, still I
  can't "having stopped maintaining intoxication, achieve liberation of
  mind".
  
  -- All these thoughts, friend Anuruddha, of the kind "I try and look at things with purified Heavenly Eye, I try and see things with
  thousandfold-superhuman vision" -- this is your conceit.
  
  And the thoughts of the kind "I train in confidence unmovable, in
  awareness undimmable, in tranquillity imperturbable, and in focused
  mind unscattered" -- this is your pathologic restlessness.
  
  And the thoughts of the kind "still I can't "having stopped
  maintaining intoxication, achieve liberation of mind" -- this is your
  remorse.
  
  You'd better, friend Anuruddha, these three dharmas abandon; To these
  three dharmas not attending, the deathless aspect assemble with mind.


Here "the deathless aspect" (amrita-dhatu) refers to Nirvana, in this context also described as vajradhatu, "the indestructible space that accommodates everything, samsara and nirvana. Nothing can challenge this space. In spite of its clarity, or discriminating wisdom, it is still indestructible." (Chogyam Trungpa)

"see ourselves as we really are", "engage directly with reality" and "grasp enlightenment" -- all refer to the same thing. This is when "compassion" happens naturally. In order for this to happen, one has to "remove wrong perceptions", "remove all entertainment and distractions" -- which includes removing the notion of goal or attainment, hence "no starting point nor goal, nothing to attain" without any trace of "eventually".