Pre-conceptions will ruin anything for a person. Very important in the "hobby" that we are all part of to reason ourselves out of the pre-conceptions to try and ensure we can enjoy something.
Well, there's preconceptions and there's preconceptions.
There's a degree of preconception where, for example, it's unrealistic and you're bound to be disappointed. In the realm of comic book movies, I'd say a good example would be expecting complete 100% fidelity to the source material, down to the spandex outfits with perfectly defined musculature. It's just not gonna happen. The films are always adaptations rather than 1:1 reproductions.
But it's still fair to expect that the core of the characters will remain mostly intact from what came before. Again, in the comic book realm, this means things like, you know, Batman doesn't kill, or if he does, it's either (A) accidental, or (B) specifically noted as being different from his M.O. or something he moves away from or something. Or it means, for example, that Steve Rogers' Captain America isn't a jingoistic, brutal "Team America: World Police" type who's willing to use lethal force even when he doesn't need to (that'd be more appropriate for John Walker, a.k.a. Super Patriot, a.k.a. Cap's replacement).
With the Trek films, the core of what made Trek what it was, and what made the characters who they were, was stripped out and replaced with generic action movie tropes. They're well-made action movies, good ripping yarns that entertain as roller coaster rides, but...they aren't really Star Trek. That's also not to say that the "real" Trek films that preceded them were all that much better at capturing what made Trek Trek every time, but at least they were trying. These films actively try to move away from that, while making nods to only the most superficial, overt aspects of the franchise. They're Trek for people who are only passingly familiar with Trek. That's by design.
But I think, as I've said before, that these movies were really just filling a void, which is now being filled with its original inhabitant: Star Wars. This has had the effect of crowding Trek out, coupled with the fact that the old school fans have started to lose interest in this iteration. Action Trek, or Generic Space Adventure Film Series, is fine for what it is...but it isn't Trek and I think the more "casual" audience just doesn't really care much one way or the other, and is happy to shift their allegiances to franchises with which they're more familiar or which do this stuff a little bit better.
