and I think Punk himself has said he prefers to be a heel. it's more natural to him.
and it's kind of ironic, since I'm a Superman fan. if you compare Punk to John Cena, people will say Cena is more the "Superman" character while Punk is more like "Batman."
I don't dislike "Superman Cena," but I just feel he needs that "tough edge" that he's lacking.
and maybe that's why I'm liking the MOS Superman. Look at the recent Superman images. They portray strength, toughness, and the sense that this Superman means business.