From the looks of it, most devs aren't bothering to include multiplayer unless they also include wifi support.
With Tetris, Hunters, Bomberman, MK, AC all going wifi, it's rapidly getting to the point where a game will be looked down upon for NOT having online support.
Most xbox games suffer this problem. If there's no live support, people subtract points from it's score (if it was a game with multiplayer, that is).