I'm not sure moving to the big screen was a mistake. But going straight to the big screen was. There was no time for general audiences to 'miss' the characters plus they were still competing with weekly adventures of two series.
Voyager should have been delayed til DS9 ended and the TNG movies shouldn't have premiered until 24-36 months after "All Good Things..."
Good points, I agree. It could almost be seen as a cash grab because now we have to go to the theater to see something we could once watch for free. But with most paying for either cable or dish TV we were paying for it, so what do I know?