I'd have to say Insurrection
sunk the TNG films. I don't dis
like the movie, but it doesn't do anything for me. When I went to see the INS, it was in a full theater and I could tell it didn't do anything for a lot of people in the theater either, especially when I overheard people talking about what they thought afterward.
INS killed any momentum the TNG films had after FC. By the time NEM came around, four years later, no one cared anymore. The theater I went into was only half-full. There were also newer and better film franchises emerging by then. It's as simple as that.