Because for people like me, unconscious zombie-like bears who will dig through concrete walls with bare hands in order to quiesce the source of the disturbance of my crucial slumber, while maintaining no memory of the demolished wall should I be successfully woken 10 seconds later, easily shut off devices simply have no effect.

I've woken up a few times on the floor curled around the power cord to the alarm clock, torn from the wall (or to find a phone in 15 pieces and a new dent in the wall).. many, many people like me