I think ALL drugs should be legalized. Think of it this way, when alcohol was illegal in Early 20th century US, it was basically an invitation for all kinds of criminal elements to come in and profit from it. And they did! But not only that, they had turf wars, the likes of which we see today over drugs. If you could get some weak heroin that had some sort of additive that would make it harder for you to get addicted, marijuana, or cocaine at a pharmacy, it would make it harder for criminals to profit from the drug trade. You'd have less drug dealers loitering, dealing to kids, etc.
Make the laws much like the alcohol laws, if you get caught doing it in public or if you're acting like a buffoon in public while on it, you get a ticket.
Plus it would save local and the Federal Govt. a LOT of money on prosecuting drug cases. Drug using is most often a consensual crime that hurts primarily the user. Sure it spills over into the lives of others sometimes, but the fact that there is such a stigma attached to it makes it harder for people to get help. If it were decriminalized, I don't think people would think twice about going to rehab if they found they had a problem.
Fact is, you can't and shouldn't try to protect everyone from themselves.