It's not about heroin. It's about oxy, weed, coke, etc.
This forum is not exactly anonymous, so I'll restrain from full commitment, but I will say that my threshold for trying things like X, cocaine, etc. in a safe, social setting would be negligible if they were completely legal, say, in my own home. What happens next? Maybe not me, but a dozen other people just like me, in a similar setting would become addicts.
Furthermore, I understand that this war on drugs will never be won, but I don't want to live in the first major Western country which legalizes these things. It'll be like Vegas for gamblers. Certain cities will become straight-up drug dens. Let some other countries play around with this, like Amsterdam.
Addiction is not some hard line we all have to jump over. I don't at all consider myself to have an addictive personality type. Have no problem controlling my EtOH, and I have never been interested in cigarettes. Nonetheless, I had my wisdoms out about 10 yrs ago, and within 4 days I managed to time the doses so I never felt pain. I was riding the buzz, calling in a refill less than a week after it was dispensed. I had the willpower to never pick it up, and basically stopped when the bottle ran out. But if someone like Brett Favre can get addicted, just about any one of us can.
Like it or not, the illegality of drugs is a hard line that prevents many more people from using on a regular basis.