My view on this is that if it was legal to have some of this stuff that it would not appeal to alot of the users because it isnt cool anymore...
For example, younger people such as high schoolers, try to go to parties where they can drink and you are 'cool' because you were able to get ahold of beer or what ever the beverage might be, but if your parents make this avaibable to you and tell you just dont drink but you can have all you want, then I bet that kid drinks alot less over the long run than those kids that have to be sneaky and do illegal things just to get it...
I think it would work the same way with some of our illegal drugs...but the strong ones hey why not legalize those to because then you would have some darwinism going on and we wouldnt have as many retarded people walking around...