Personally, I think MP has been ruining FPS. A lot of them nowadays seem focused on MP and just some quick and thoughtless SP campaign. I guess I still remember stuff like the original COD games and Medal of Honor games where I thought the SP was stellar. I rarely play MP. Just not very good and don't really care about stats or stuff like that. I do like co-op but that isn't a focus of these games either.
That irks me too. I'm not a fan of co-op though, mainly because I don't know many people to play with.