Outside of guild matches or playing with friends it doesn't seem like voice chat is ever used in games these days... I play Battledfield 3 and, while I chat with my buddy, I almost never hear anyone else speak in those games, and on the rare occasion that I do it's generally some heavy breathing 12 year old.
None of these are really surprises to me... Still looks like a lot of fun. Why would anyone expect CPU stand ins on multiplayer?
It does make me curious what the 1player mode will be like though.