I will never understand why people read critic's reviews. If you want to know about the movie before you watch it, read a synopsis, or a recap. Do people really think that someone else's opinion about a movie is any better or worse than their own?
Forming an opinion based on someone else's opinion (especially if you never even see the movie yourself) is a shortcut to thinking.
There are many aspects involved in this. For example: I like to read them because it is a habit (which does not influence my opinions about the movies I watch). I like to read and notice different perspectives, but always keeping my own intact.
Unfortunately, there are millions of people who think that way.