I think you are confusing Castle Crashers with some other game. Castle Crashers is and old-school beat them up with very nice art.

Also, the problem you describe exists in all entertainment industries. I don't think we've innovated much in literature since Shakespeare or in cinema since Hitchcock. But there's always some work that stand above the rest in their originality. And then a lot of other works that improve on them or at least try. I don't think that's bad.