I completely disagree. I've got a laptop with a touch screen, and it's occasionally very useful. It's rarely my primary input method, but when you're not constantly using the mouse, how often do you lose track of where the mouse cursor is? Instead of reaching for the mouse, figuring out where the cursor is, and then carefully maneuvering it over the button I want to click, I can just reach out to the screen.

A touch screen is incredibly useful when you're not currently already holding your mouse. It's easier to switch from keyboard to touch than from keyboard to mouse.