> 1. Why has the mouse remained so popular when it's clearly inferior to
> just directly pointing (even with a stylus)?  Surely the technology of
> the digitizer has gotten much cheaper over the years.  It 
> can't be just a cost issue anymore.

Hand-eye coordination for one thing. Positioning the cursor sucks with a
tablet if you can't move your hand towards what you look at. I think that's
why most successful "off-screen" positioning devices are relative and not
absolute. In addition a tablet which isn't the display itself requires extra
space and so you have to move your hand pretty far away to get to the right
position (I have to lean over in order to get to the upper right corner of
the screen on my Wacom).

A good bit of reinforcement by the UIs for another. If you've ever been
using the MS tablet PC one of the first things that you notice is how badly
Windows is designed for use with a pen. I find it almost unusable with a
pen.

Cheers,
  - Andreas