I do recall reading that there was some belief put to Smallville may have weakened the film because of people going by the same reason Berman had TNG cancelled after season seven: why would people go see it if they can watch it from home for free?
What???? Ending TNG was Paramount's decision because it got costlier to produce each season. Ending one show and starting another let them make new, more profitable deals, and a new cast meant smaller salaries. Actors get raises every season, so the longer a show stays on, the costlier it gets. That's why very few shows go beyond seven seasons, and those that do almost always have heavy cast turnaround (including Smallville
, which has only two original cast members remaining).
I remember where I heard it. It was on that Behind the Scenes program E! used to way back when they first started. I just found the video (being a packrat is insane) and Berman says one of the reasons that TNG ended was they wanted to make it into a movie property and they were worried that being able to watch it on television would hurt ticket sales. It's during a scene where they show a behind the scenes clip from Lessons.