Addiction and dependency are separate issue when dealing with drugs. I am physically dependent on opiates. When I was a child I was hit by a truck and bashed up pretty good. It pretty much ruined my neck. Anyway, in the absence of my medication I don't jump to the I need to commit a crime to get it nor would I. Addiction is a psychological phenomenon in which the user becomes consumed with the drug and will do anything to get it, it is a compulsive disorder and has nothing to do with the actual drug. If Alcohol where illegal an therefore prohibitively expensive you would see the same behavior among addictive personnel with Alcohol. Just because someone is physically dependent whether an abuser or not does not mean that they exhibit addictive personality traits.

I don't know about the legalization of Heroin, crack and Crystal Meth, I don't know enough about them to form a factual based opinion on their legalization, but I do believe without a doubt that Opium, Marijuana and Coca should be legalized immediately. The possession of a plant being illegal is ridiculous and the fear mongering around these weaker formed was unfounded in the first place.

But then the trouble is that you broke into someone's house, not that you were on heroin.

I think it'd be reasonable to make the penalty for crimes committed under the influence to be equivalent to conciously choosing to commit the crime. This seems to solve that issue to me.

I've known several heroin users and not one ever committed a crime to support their habit. As others have pointed out, penalize people for the crimes actually committed, not for what some people think they might do.