Flying too slowly is far more dangerous than any other sort of flight; loads of people die from stalling/spinning. That's is probably why it is taught; to show how to fly on the back of the curve.
I don't think for a moment that slow flight is taught to give somebody more time to think. One is far better off flying at Vbg (=Vy) than very slowly; flying just above Vs overheats the engine and blocks your forward view.