I think it was Confucius who counseled rulers to not outlaw what they could not reasonably control.
Whether cannabis cures cancer or turns normal people into walkers from The Walking Dead, it's a plant. It can be readily cultivated anywhere there's a growing season of four months or longer (i.e., most of the United States) and indoors anywhere. No special equipment is required to process cannabis. You just pick the buds, crush them, and roll them into a cigarette and smoke it. That's all there is to it. (Granted, to make high-value, commercial grows is a bit more of an undertaking, but you don't have to grow high-end weed to simply get high.)
Therefore, the war on marijuana never really made much sense. It's pissing into the wind. And, as others have pointed out, marijuana isn't any more dangerous than alcohol and tobacco.