Im terminally lazy....
One mouse click as opposed to two keys having to be pressed just makes more sense to me
yeah, i'd rather move my mouse 3 cm and click, than lift up my whole arm, which would be resting on my leg / desk.
I guess that's why my right arm looks a tad more muscular than my left
If you are lazy not moving your hand to the mouse is the easier thing to do especially as it is more likely both hands are above they keyboard (unless playing a FPS).
What does?
Mine is saved for Compiz related stuff. Well in distros other than Ubuntu.
I think I only use it to lock when I leave my desk ...