I won't respond to all of your thoughtful post, Samuel, because it would take me all night, and I've got a user interface to design. :)

However, I would just mention one thing. All users are alike in one respect: they are humans and they think like humans, not like computers and not like programs.

The beginning of "About Face" talks about how we should model our interfaces after human concerns, not computer concerns. And that too often, we make design decisions to make it easier on programmers, rather than users.

Once we've broken away from desiging around the implementation rather than the user, then we can talk about specific users (which you did so aptly). And Cooper does this, too. I especially liked his description of the "perpetual intermediate," into which category I think most users fall.

But not all. And that's why, for example, Cooper insists that we provide different ways to do things for different types of users (like having both menus and hotkeys). He also urges us to write software so that the program can learn about the user, instead of having to be told every damn thing in a dialog box. :)