Heh, yeah. And that's a good point, too -- the face buttons could still be used even for things like healing spells, come to think of it. Trap laying, etc. Even area-of-effect spells if it's not something that has to be targeted at all. The only thing you can't do while aiming is use any face buttons, and vice-versa, but there's plenty of stuff that requires no aim like the above. Interesting!
In terms of playing FPS games with just the keyboard... yeah, I used to do that, and I had a really hard time of it. I played Wolfenstein 3D, Duke Nukem 3D, Quake 1, Quake 2, and Descent all that way. Then later I figured out what all the fuss about WASD was, and never looked back. I went from struggling on the second from the bottom difficulty in Quake 2 to being able to reliably beat the top difficulty.
Hence... why I'm not to excited about keyboard-only direct-aiming, and why we focus on the targeting mode for that more. But, if there's somebody who really wants that mode, then they will be a good source for refining it when the time comes!