I like achievements, another food pellet that gaming can give me to reward good behavior is always a welcome addition. but I've never been one to worry about getting a 100% completion rate (there's really only been a few games where I've actively tried for 100%, Mass Effect 2 and Pokemon being on that list.) So my thinking is that multiplayer achievements are more of that. A nice reward to validate time lost, nothing really beyond that. not really worth getting worked up over.