I agree with Thomas. I fear that if drugs were made legal, there would be so many more people willing to try them.
The risk of physical harm to a first-time, or just a "social" user, is higher than with alcohol--addiction or possibly even death.
Though legalizing drugs may initially reduce a user's need to steal to obtain drug money, people under the influence of drugs do commit crimes. Not to mention the danger of driving under the influence of drugs.
Education is the far better answer.