The only things that should be "banned" are those that are so intrinsically harmful they cause severe, immediate, measurable harm to both the abuser and society.
There aren't many drugs that people consume that qualify for this standard since to be able to continuously abuse something it can't kill you the first try.
Firstly, substances can be used without 'abuse'. Alcohol is a good example of this, you probably know many users who never abuse it. Alcohol most certainly can cause severe, immediate harm to the abuser an society.
Why ban substances based on harm? Why not just enforce the rules around the actual harm?
For example, enforce driving under the influence and don't ban alcohol.
Is there really a need to ban things like heroin which have a high rate of causing harm to the user? It seems like it is more of social and community issue. Throwing that person in jail is hardly improving their life.
In terms of priorities it should be avoiding harm to others, such as not driving under the influence as you suggest, and then avoiding harm to the individual, as might be the case with a chronic alcoholic.
As a note, heroin isn't as inherently harmful as it's made out to be, but, like other things, so long as it's illegal it will really only be popular with the more hard-core drug users. It was legal before, after all.
Almost nobody does though because there is a legal form from which to get the high that is a minute fraction of what is required to kill you.
I'm not sure about the USA, but in Canada, the number of people who use marijuana and the number of people who use tobacco are almost equal, despite only one of those substances being legal. That seems to indicate to me that the laws have no impact on consumption or the limitation thereof.
If you are worried about the effects of people using drugs, you are already witnessing them.
If we start banning substances rationally, wouldn't cigarettes top the list.