I realize that most, if not all, of this may have been said before but:
The TOS movies are, in general, better than the TNG movies because they were created as movies (except for TMP) while the TNG movies were written as two hour long TV episodes with a bigger budget. All of the TNG movies have this problem, they are structured no different than the series are almost the 8th season of the show. They have an A-Story and a B-Story and use their extra time to put a little more characterization into each. The fact that the A-Story centers around Picard and the B-Story is usually about Data doesn't help in the slightest. Even the best of the TNG films, First Contact could easily have been done as a two part episode, albeit on a much smaller scale.