Why does everybody hate John Cena?

Cena hate has died down in the last few years. Most of his hate has been because of his awful Superman like character and the fact that most people think he can't wrestle. I don't like him but don't hate him, I respect all that he's accomplished and have enjoyed some of his matches (his WM vs Batista was good) my only real problem with him is his gimmick. It's too cringe inducing and he sucks up too much to the fans.