The way we currently play, which has a strong chance of being the way we ship, is to let players zoom and rotate even in MP. What Swinger pointed out is that players rarely do it anyway.
Why? In AOM, you don't have to play the camera. (In many of our games, you don't even have time!) Your units will never be obstructed where you can't see them, and no one is ever going to surprise you by attacking from an angle you can't see (why that sounds reasonably cool, I think camera control schemes are a long way off from making that manageable).
Players who resign or get beat, or those playing single player, do often use the camera, just to get a cool shot of a particular scene. Cinematics, of course, make a lot of use of the camera.