They should be decriminalized but that's as far as it goes. You would be absolutely crazy if you think it's alright for people to buy LSD and mushrooms off the shelves. Drinking and driving is bad enough as it is. Think of the implications of allowing drugs on shelves even for a couple of seconds and you'll realize just how bad of an idea that is.
Think of the implications we currently experience by allowing the continuation in black market sales of illicit drugs. There are huge benefits to be had with the controlled sale of narcotics.