With the added complexity of making it mulitplayer you would also have to deal with the increased costs of keeping the game running. Right now when they finish

With the added complexity of making it mulitplayer you would also have to deal with the increased costs of keeping the game running. Right now when they finish a game the only recurring costs they pay is hosting,bandwidth,and support. If the game fails , except for hosting , those costs would go down (less people buying game means less support etc). But if a multiplayer game fails you have to keep the servers running or risk pissing off the people who bought the game