Come on. The corners are used to bring up a touch-centric UI element to compensate for the fact that sliding my thumb in from the right hand side of my 20" desktop LCD screen won't do anything.
Yes, the corners aren't touch UI elements. They're just used exclusively to bring touch UI elements onto the screen. Same difference.
So now the problem isn't the corners, but it's the menus they bring up? Are you saying it's difficult to click the buttons on the charms bar? I just don't see where the "forcing a touch UI upon users" thing comes in. If you could only bring up the bars by simulating touches via click-and-drag, I'd see your point.