What are some examples of an interesting movie premise being ruined by the presence of a movie star?

I recently read about how the film I Robot was originally supposed to be a more lowkey and intellectual project before Will Smith came on board and the studio decided to needed to up the action and do away with much of the philosophical elements. It made me think about other movies that had cool ideas that were never fully realized due to the presence of a movie star. Demolition Man popped in my head. The original Judge Dredd popped in my head.

What movies can you think of that would have been much better if they focused more on the cool premise than trying to get cool shots of its star.