I honestly can't stand it when MP is added to a game that should be purely SP campaign. I was put off instantly when the announced MP for Tomb Raider.
Developers get to excited about MP nowadays and add it without truly thinking about how it will impact the quality of the game. So much time and resources must be put into it that it spoils a lot of games. I still believe Mass Effect 3's bad ending was partly a result of putting time into MP instead of concentrating efforts on bringing the story to a proper conclusion.
As for MP achievements... Get rid entirely. The end.