I recently watched the TNG films again, and I can say that Generations is probably "the best". Which isn't saying much because all four have severe problems. But this one at least feels like an event picture.
Both FC and INS are simply too small. Yes, FC too. As I've said often, it's essentially a bottle show and a missed opportunity to make the return of the Borg something epic (I do hope that the next Bad Robot film will use the Borg and make them interesting again). There's also narrative smallness in the character of the Borg Queen, who reduces the Borg to a bunch of zombie henchmen to an EEEEVIL seductress who cannot express herself except in double entendre and confusing hogwash disguised as mind-bending philosophy. Nah.
Compared to that, NEM actually holds up pretty well. It's a copy-and-paste job of previous films, yes, and the villain doesn't make much sense, but then again, neither did some that came before him. The cast interactions, on the other hand, are really good in this one and, in contrast to its two immediate predecessors, at least an attempt was made to make the film cinematic.
So was TNG on the silver screen a mistake? Well, no. It was the logical thing to do once the original cast had retired. No other big-screen Trek could've been made at the time. And seeing how the TV shows fizzled out a few years later, that might've been the absolute end for ST altogether. The films, mixed bag that they were in the TNG era, at least kept the general public aware that there was a thing called Star Trek - which could then be revived to great effect in 2009. But it would've been nicer if the TNG films had kept the high quality of the series.
I blame committee writing for this. Too many cooks, too many opinions on what kind of narrative and what kind of scope a ST film should have. Plus: Rick Berman, who I dare say was in over his head with movie-producing.