I'd have to say Insurrection sunk the TNG films. I don't dislike the movie, but it doesn't do anything for me.
Do you realize the power of what you wrote?
That is absolutely the most condemning thing anyone could say. To say that after $60 million and thousands of hours labor they instilled within you a feeling of indifference.
Wow!
People, by our nature, are prone to feel something. It is only an extreme case when something leaves us feeling nothing. There can be no solace or upshot to that from the point-of-view of the cast or crew. That makes it an unqualified failure for all concerned.
And I think people have it wrong to say "there was no place to go." They had an exceptional mix of characters and the univesere literally as their metaphorical oyster. Star Trek (TNG included) could go anywhere and do anything it wanted. It is, by design, uniquely crafted to tell any kind of story imaginable.
As for the aging, again I claim bull-schtick! The TOS folks did it. They did it by simply aknowledging their age and embracing it. That is all TNG had to do.
The Riker-Troi wedding meant nothing because they never really laid the groundwork for it to mean something. Fans tried to make something out of it because they had all this outside information that general audiences didn't. And that kind of symbolises TNG's big screen problems - all their movies (save First Contact) were all about taking short-cuts.
TWoK, for example, culled a villian from TOS run on TV roughly 15 years earlier which organically created a tension and a gravity to the drama. TNG, in Nemesis, tried to manufacture the same relationship between Picard and Shinzon in an instant and it felt painfully contrived. Just as Data's mock sacrifice tried to recreate Mr. Spock's powerful death scene also in TWoK.
No, what killed the TNG films was the total taking for granted the wonderfulness of what they had by all concerned taking shortcuts. The lack of quality which resulted was seen and felt. In short, it was a suicide.