How do you know that most people who have played Final Fantasy 13 hate the game?
On the Internet? Sure, it has become a cool thing to do to bash it. That was not the case when the game was released, the internet warriors developed this attitude a few months after release and it became common. Edit: SE terrible reputation didn't help either, they made some of the worst decision in the recent years. People were hating on SE through XIII.
It is a good game with its share of flaws.