People like fast paced, high damage games. For all the smart system reasons people give for liking GG more than BB, I think that's the main reason ultimately. It's one of the reasons the sluggish Skullgirls died a death. And while it might not be the reason P4A is enjoying such early success, it will certainly be one of the reasons people keep playing it. It's 10x more fun just to move around and hit buttons in than BB ever was. It being simpler is probably a valid argument (some of the rushdown looks particularly braindead) but I don't think that's ever really influenced most people's opinions. It's all about how fun it feels on an intuitive level... SF4 gets a pass because it has Ryu in it, which is a shame since I like the SF games where it's not like playing in molasses.
