Have you ever heard one Mac user say "Gee, what we need is a round ball that you click that lists the contents of your applications folder?"? But of course we do need to be sure that what we replace it with is better from a UI perspective. I agree with you that we aren't to the touch pad, kinect, touch screen phase in the PC world yet and it's not clear that will end up the direction. The Metro developers clearly believe that it is the direction, but for the operating system to lead rather than follow is dangerous.
Apple is moving iOS and OS X back together, but they are doing it in steps, making sure that the hardware & software work together in a logical way. Microsoft seems bound and determined to skip all those steps in between and plunk a fully developed unified desktop/tablet OS down this year.