As much as an advocate as I am, I would still be pretty damned wary of making ALL drugs legal. The idea of going town to the local Rite-Aid to pick up a gram of meth might be appealing to the average meth user, but I tend to group drugs into categories of good and bad. Not all drug policy is misguided, despite that a large portion of it is. Things like cocaine and heroin are genuinely destructive, as can be seen in most long-term cases of use. Drugs like acid and mushrooms are more physically benign, but making them available to the entire public might show more problems relating to the mental aspect of it.
Marijuana has a good case because it doesn't really do anything too significant and the health risks are low in comparison to smoking and alcohol. When you go higher up, you run the risk of being physically fucked up by hard drugs, or mentally by hallucinogens. I would support the legalization of marijuana and less strict laws for the stronger drugs, but not outright legalization.