I think people that say legalize everything cause of free market and all don't realize how complex this issue actually is.
I prefer there to be classes of drugs based on addictive potential, social utility, physical harm, ability to function, etc. For example:
Legal & restricted...
Tobacco: entrenched in our history and long-term health effects.
Alcohol: entrenched in our history and can be addicted, but can be used in MODERATION easily and is a social lubricant.
Pot: not much different than tobacco, and can help those with pain.
Borderline...
Hallucinogenics & MDMA: not very addictive, cannot function in society but lasts short periods
Illegal...
Methamphetamine, crack cocaine, PCP, GHB, heroin, etc.: can be extremely addictive in short period of time, several physical and mental deterioation, cannot work in society and thus more likely to lead to crime to obtain more drugs, start caring about personal health can health of dependents, not entrenched in society, cannot be used easily in moderation, promotes isolation rather than being a social lubricant.
I used to be addicted to meth. I stopped caring about myself and everybody around me. Good thing I didn't have children. My wife and family was crushed. I spent all of our money on drugs. I was constantly sick. It made me paranoid and I barely slept, also putting others in danger when driving. What was the benefit? At first I had more energy but that was it.
So, why should we legalize EVERYTHING? Our current policies attack the supply, not the demand. Why not fix that? The system is not perfect, but do you really think people will just "experiment" with hard drugs? No. They aren't like smoking a joint. If there is easy access to these highly addictive substances, the chances of people getting hooked are much much higher than other drugs and/or they have no social utility.