I wouldn't go so far as to say leave it to FPS games, but yeah MMO PvP is pretty bottom of the barrel. If you're gonna do PvP you really have to build your entire game around it, and I don't know of many MMOs that have done that. The mechanics and game design choices that work for PvE usually don't mesh well with the needs of PvP, so trying to tack on a PvP section in a game that's been built primarily for PvE is just foolish. I wish more developers would recognize that and focus on one or the other so we'd all get better experiences.