If you ask me, the anti-drug laws shouldn't be in place because of the addictive quality, the organized crime, or how they are harmful to the body, but because they can't be regulated like alcohol or tobacco. You stop producing cigarette smoke as soon as you put it out and alcohol passes through your system completely in a couple of hours, but lots of drugs stay in your system for months after the effects have worn off. This makes it difficult to conclusively prove weather someone is still impaired by the drugs. So what would be done if they were legalized? Make it like cigarette smoke and just don't do it in certain places? They are still impaired, and depending on the drug, anywhere from extremely mellow, to extremely violent, to just f*****g crazy. And what about driving restrictions, like with alcohol? It would mean if you have done drugs at any time in the last few months, it would register just as if you had been doing them a couple of minutes ago.
A lot of things can be considered addictive, with very few of them actually being a physical depencency.
Legalizing only certain drugs wouldn't do much to drug crimes. So long as the harder drugs are still illegal, the cartels will never go away.
If someone wants to harm their own body, I say let them. At least in the United States, this is supposed to be included in freedom of choice. I won't speak for whatever might work in another country, though. Every culture is different.
That being said, I don't see this changing anything, at least in the US. The "drugs/smoking/alcohol are bad" message has been beat into our head for decades, and people still choose to use them anyways. Not much farther it can be taken until you hit full-blown brainwashing.