I think multitouch is great for manipulating 2D objects like photos. You can perform manipulation of 3 separate functions at the same time and intuitively compared with single touch: move, rotate and zoom.

This isn't necessary for most other operations (browsing, email, file operations, etc). So.. horses for courses.. etc.

Btw, double-tap/zoom-to-the-div's-width is a NECESSITY for a device with 3.5" screen