No, no. It's not the dumbing down to a wider audience that hurt Trek. NuTrek fans will certainly tell you. What hurt the TNG films was self-indulgance. Patrick Stewart's performance in First Contact was so good he got creative credit for everything after. And sure enough, the original story for the follow up was shelved because Patrick didn't like it. Everyone else including the other actors, the studio and even Rick Berman liked it, but not Patrick, and he got it changed. Unfortunately circumstances creeped up that allowed that same mistake to happen again. After Insurrection, Stewart got involved with the successful X-Men movie and now he's regarded as a box office draw.
How about an eight to ten episode season on TV where Trek belongs, where they can take the time to tell the story and focus on the characters? Hell I would love to see a show about Riker onboard the Titan with Troi and new characters.
OK, I'll mention a plotline: see if it doesn't' sound familiar
An enemy from the captians past resurfaces, and acquires a deadly and powerful weapon he intends to use to revenge himself against the captian and his federation.
After a great sacrifice, the old enemy is defeated...but at a great loss.
Same movie. FOUR times!
Extra points if you can rattle off the titles this plot was used in.