In theory, I completely agree with you. In practice, I dunno. If we become more reasonable and tolerant of drug use, we'll end up subsidizing the drug user, one way or another. We've already seen that drug abuse treatment is now a required employee health benefit. What next? Are we going to pay lifetime maintenance benefits to support the lifestyle?
If the real social consequences were death in a ditch and we were willing to tolerate that, then I'd say, "OK". But in today's world, we'd be exchanging a law enforcement activity for a social welfare endowment -- a la Britain. There is not sufficient social stigma in that system to curb the behavior.
So look at the places where drugs are legal or where drug law enforcement is very lax. They are no worse off - mostly better off - than our inner cities where drug gangs fight over turf.
When was the last time someone was murdered over a vineyard or brewery?