A touch screen keyboard is just fine for cellphones seeing as you're using it while looking at the screen at the same already, thus you see the keyboard at all times in the bargain. For a computer though, it is utterly useless and stupid. How would anybody touch type if the keyboard were a flat piece of glass?
Apart from the added costs, added power draw and added weight, it does nothing for the functionality of the computer, and in my opinion, it even impedes it. It's simply not going to happen.