> Touch-screen interfaces today are anything but "perfectly designed".

I don't disagree.

However, a mouse will always be more versatile than a touchscreen. There's a finite theoretical ceiling for touchscreens that's well underneath that of mice. Even looking beyond the completely-obvious fact that there's no real way to distinguish between "point" and "drag" on a touchscreen (other than "did this start on a draggable element", which is far from ideal), two fingers and a thumb can readily control five separate buttons plus a scrollwheel, and I can add even more buttons to a mouse.

I can't add more fingers for touchscreens.