One thing to consider here, is the addictiveness of many drugs has to do with the purity. If meth is over 60% pure, then the addiction rate goes WAY up. Legalization is one way of managing the purity.
Maybe. Though if you ban meth that's >60% pure but allow meth <60% pure, really all you're doing is drawing the line on what is allowed and what isn't in a slightly different location. The linked article seems to be arguing that all drugs should be legal, regardless of how addictive they are or are not.