Of mice and trackpads

Slowly but surely Apple's multi-touch trackpads make mice look really bad:
  • Gestures take a bit to learn, but are very efficient. They are also a perfect preparation for a true multi-touch user interface for Macintoshes.
  • The new button-less trackpad design is great for gestures.
  • The Mighty Mouse track ball (German: Dreckball) gets dirty and stuck really easily. So much so that this is a known problem in Apple tech support circles and that there are a number of solutions floating around where some work better than others.
Thus, the next logical step for Apple is to have a “solid state” Mighty Mouse: It would have no movable parts, especially no track ball, which would be replaced by a trackpad on the front of the mouse. But that begs the question: Why have a mouse then, why not just have a trackpad?
Update: After having played with the new trackpad, it came to me: Apple hasn't eliminated the button, it has eliminated the trackpad (while adding sensors to the button). The cool thing is that this gives you gestures for clicking: For example, for right-clicking you put two fingers down while clicking. The old button could not detect gestures, so this wasn't an option before.