The problem is they generally use E and F for something, which results in a cascade of rebinding.
And yeah, tablets are better, but they're also more expensive and don't do other mice things. For how rarely I do 3D modeling and whatnot (pretty rare), making sure my mouse has a middle button is plenty.
And yeah, I much prefer controller, even for FPS since I don't play competitively (even then, I've seen awesome videos about gyro aiming).