We've entered an era where opinions on films are debated more, it seems. People care more nowadays when the general consensus of a film doesn't fit their own thoughts, for whatever reason. Therefore the perception is it's more polarised. The reality is it's the same as before with a broad range of opinions, but now we care more about ones that differ to us.
It's a bit strange really the rhetoric over this film. First the massive hype, then the big backlash. All the weird detailed theories about what it means when there isn't really that much depth to it. The same basic story has been done to death in film since Taxi Driver, but without the joker. We all have so many preconceptions about what this movie about a comic book character was before we even watched it. The skeptic in me thinks it's just a really good marketing campaign at work, but it's probably more than that.