Here's a question for you: Can a movie ruin a good review? Conversely, can a review actually improve upon a movie? Sure, good criticism (whether positive or negative) should encourage you to see a film in new ways you may not have recognized before. Just as cinema itself is a way of looking at the world through someone else's eyes, criticism is a way of looking at movies through someone else's eyes. Yet, the movies themselves don't change -- only our perceptions of them (we'll put aside William Friedkin's "French Connection" Blu-ray for the moment). On the one hand, a piece of film criticism is kind of like an adaptation. It offers an interpretation of the original, but does not replace it. Other "versions" still exist, just as they always did.
I can think of several examples of criticism that I think is superior to the work being criticized, in the sense that the critic is writing about an idealized version of what's on the screen -- the movie we might wish was on the screen, rather than (or in addition to) the one that's actually there. A clarification: This has nothing to do with whether the critic is divining the filmmaker's intentions or not. It has everything to do with what the critic is seeing in, and getting out of, the film.