I guess it is more important on the smaller devices like the ipod touch where you are constantly zooming. Still, like I said, there is no reason not to have it. It doesn't detract from the user experience. I think the Palm Pre makes hte best use of it, with the gesture area on the bottom allowing you to launch apps without leaving full screen, as well as the gesture to switch between app windows.

Multitouch is also important for games.