From what I remember reading, the .357 was developed for the police who wanted a round that would penetrete an engine block. Considering the engines of the time, the Mag. would do it. The truth of this, I am not sure of.
Actually, I recall reading years ago it was wanting a round to penetrate the thick body panels of cars is why a more powerful round was developed. My theory is it was borne form the "bigger, better, faster" nature of the human species.
Now I'd like to hear Leo's buddy tell why it's called ".38 Special" since the bullet diameter is .357".
It wouldn't have anything to do with the evolution of lengthening the heel based, reduced diameter shank .38 rounds (which were true 0.38" diameter) and replacing with a .357" inside lubricated bullet while retaining the same outside case dimensions... would it?