"Utopian fantasies"? Hyperbole much? 
Newsflash: prior to the Harrison Narcotics Act of 1914, governments did exactly that. Yes, people were addicted, but no, people did not regularly die of their addictions. That started regularly happening once narcotics were made illegal and the trade was essentially given to the black market to exploit. 
Addiction-related crime and death really took off when Harry Anslinger's US Treasury-based narcotics control board decided to prosecute doctors for prescribing heroin to existing addicts, which was explicitly allowed by the Harrison Act.
Although none of the charges stuck in court, doctors were spooked enough that they cut off all their patients. 
THEN people started dying, for the same reason they do today: because they couldn't predict the strength or content of their drugs. People on stable doses of opioids don't simply die as a matter of course, y'know.
If you have a different perspective, I invite you to share your reasoning.