I'm confident I missed many aspects here, although really interested in: What are the problems with this model?
Basic medical education should be provided as part of national education. Except, properly done, not the factually incorrect, dramatic anti-drug programs they have these days.
There also seem to be a bias against drugs here, which I don't believe is founded in research. After all, we encourage people to get treatment for mental illnesses, the treatments which usually involve becoming addicted to very strong medications like SSRIs. Yet there's no education against being "trapped" onto such things.
I agree with the other points you've discussed.
Maybe, but it'd be easy diverting money being spent to arrest, prosecute, and imprison people into prevention and treatment (and we're already spending money on prevention and treatment from general state and federal tax money without legalization, so with legalization and no special taxes -- just general income, sales, etc., taxes -- there'd be more money from that, even before you consider repurposing the money currently being spent on the enforcement end of the drug war that would no longer be required.)
OTOH, while there are black markets for alcohol and tobacco -- largely as an effort to evade the special taxes on those products -- the special taxes on them still bring in considerable revenue, and the black market for, e.g., alcohol is far less significant and socially problematic than when alcohol was prohibited. So, its far from clear that special "sin taxes" on legalized drugs would not be useful as a significant additional revenue source for prevention and treatment activities.
Hell, I technically am in the category myself with my Suboxone treatment. My life is better than fine, and has been since I went from paying $400 a day for heroin, to $5 a day for suboxone.
My lowest points where when I was poor and addicted. I never stole, and went through withdrawals instead, but I can tell you it crosses the mind of any addict at some point. Take that away, and the impact on society is lessened considerably.
The real issue is to transition the law enforcement and prison spending to addiction treatment spending.