TWOK was the fanwankiest of TOS movies - a direct sequel to a TOS episode. It was a smash hit.
See, I think the complete opposite. They purposely brought in a director who knew nothing about TOS, and a writer who tried to figure out a villain that fans of TOS would know but that non-fans wouldn't need huge amounts of backstory in order to understand why he hates Kirk. Nobody needed to watch 'Space Seed' in order to know what was going on; Khan's backstory was dealt with in a few sentences of exposition. The rest of the movie was just a Moby Dick allegory.
FC was the most well-received of the TNG movies, and it was an incredibly fanwanky movie, with both subplots (the Borg and Zephran Cochrane) relying upon prior Trek lore.
The Borg were in the public consciousness at the time. So it was logical to make a movie about them. And while I agree that the Zefram Cochrane subplot was fanwanky, that's not what people were paying for movie tickets to see. They were paying to see Picard fight cybernetic zombies in yet another Moby Dick allegory.