I for one hate using controller, and consoles don't support M+K (ok, xbox does, but not all games do).
Playing 3d shooter on controller is just like playing it using arrow keys, possible and I was doing that when I played DOOM (the original). Tried it and hated every minute of it because of inprecise shooting.
And strategy games? Moving pointer with controller?
RTS? Is there any on consoles?
And the last but not least, what to do when one doesn't have a TV? Those are not popular nowadays :)