Maybe I'm just a cynic but I thought the 'war on drugs' had only profit taking as a goal. Sure, there has been government and private propaganda that played in to racial fears, social stigma, and religious moralities but who paid for that propaganda?
Keeping competitive natural drugs off the market benefits a few groups as does making sure your nylon, paper, and oil interests are kept secure via prohibition of the competition.
These days, there are billions of dollars to be made in keeping private prisons full and DEA agents well paid. Prohibition is an industry, and a profitable one to boot.
Ever wonder why pot is illegal in California? Some might say its because the illegal side of the market has too much to loose to allow it to be sold in a free market.
Just ask yourself who benefits from the system and you will see why it is illegal.