One of the problems in my view was a lack of change to the TNG cast. The only person to go off and come back was Worf, and that is because DS9 used his character. The TOS films were all about change. People had moved on with their lives and were facing a new and changing life situation. But they all found their way back together for the plot. TNG never did that. Granted, the films were decades after the original show had ended, but the TNG films still could have showcased that. Have Riker get his own ship, for example. Have Picard as an admiral at Starfleet or an ambassador, who is thrust back into taking command because of some threat. And it could even be Riker now in command of the Enterprise, but Picard has to come back and take command. Have Riker and Troi get married. Marry Picard and Crusher, or have their relationship developing in that direction. Anything. That would not have to happen all at once, but it could be somewhere in the film series.
TNG also did not do a lot in terms of lingering effects from the previous films on the characters. The loss of his son lingered with Kirk all the way to "The Undiscovered Country", along with a fear of getting old and being past his prime. Picard's loss of his family, and thinking about having his own family now when he never had to consider it before could be an element, and would go along with a relationship with Crusher. That could have even been an element in "Insurrection", where he is getting older, he has to consider these things, and compare the fantasy of living forever with alien girlfriend lady with the reality of accepting change and living the fullest with Crusher.