People addicted to hard drugs require treatment, leaving them to their own devices is likely to have negative results. Problem is, who is going to pay for that treatment and for how long? On top of that, is it ok for Bob the local heroine addict to shoot up in front of peoples homes in a local residential community or school? Do we really want to worry about Bob dropping his needles on the ground?
I'm not a fan of sending people to jail for drug use but when balanced against the very real repercussions to peoples lives regarding hard drug use and the affect on communities, not sure what the alternative is. Rendering down town areas unwalkable due to an infestation of addicts, and the associated uptick in property crime and robbery is not acceptable either.
Plus once drugs are legal, its very likely the first thing to be chopped in a budget crunch is going to be treatment programs as illustrated in Portugal.
Not sure what the answer is but just waving a wand and making hard drugs legal is not it.