Personally, I find the TWOK imitating didn't really begin until First Contact, but then every movie since then has drawn on TWOK in some manner, to the point STID was essentially a remake of TWOK.
That depends on how you define imitation of TWOK. If you're thinking in terms of specific plot points, maybe, but I see it more as being about the perceived obligation to put space battles in every film, and to tell stories driven by fighting evil villains who were killed at the end, and just generally to emulate the
Star Wars paradigm that TWOK was itself an imitation of. Of the post-TWOK TOS movies, the only one that really departed from this was TVH -- and, oddly enough, TFF to a limited extent, because its main antagonist wasn't really evil, and its token Klingon antagonists were won over rather than killed. (Although it still resorted to defeating the "God" entity by firing weapons at it, but I guess "Who Mourns for Adonais?" and "The Apple" did the same thing.) But Kruge and Chang were villains in the same mold as Khan, and those movies had a lot of emphasis on ships blowing up other ships and the like, even if the Trek movies generally didn't have the budget to show space battles on the same level as
Star Wars.
The TNG movies tried to be relatively more thoughtful, in the vein of the series, but they still fell back on the action-movie cliches. Soran was a tragic figure, but he still got blown up at the end. The Duras sisters were basically just there to be cartoonishly evil and get blown up (even reusing stock footage of Chang's ship's destruction). FC put a nice twist on the formula by having the
hero be the one seeking vengeance, but the villain still got killed off, and they even changed the nature of the Borg to include a character who could be a featured villain that got killed. INS tried to be a quieter, more idea-driven story like a TNG episode, but they tacked on a bunch of gratuitous space-battle stuff with Riker in the climax, and still fell back on the movie cliche of killing the bad guy at the end in a huge explosion, all of which felt incongruously imposed on the story for the sake of action-movie convention.
As for
Nemesis, yes, it was clearly emulating TWOK, but I still feel it did a
better job with the vengeance angle than TWOK did, if only because it actually allowed the adversaries to meet in person and play off each other, and because there was a more interesting, more personal connection between the captain and his foe (at least for me), more so than in any previous Trek movie. And while it did have a lot of space-battle stuff, its climactic battle in the nebula was one of the vanishingly few space battles I've ever seen that actually engaged my interest, because it was more about strategy and problem-solving and a battle of wits between two intelligent adversaries than just about death rays and explosions. I'm always more interested in problem-solving than violence, which is why my favorite action scenes are things like the rescue at the start of ENT: "Divergence."
OMG, I am *so* out of touch... 
