So would you object to those same people going down to the licensed shop at the corner and buying clean, measured, government inspected pure drug of choice. Given that chronic pain narcotic has very little evidence it provides any benefit, and very clearly any benefits are exceeded by harm. As a consequence many on chronic pain management are simply dependent on the drug. 
As with cannabis, I would prefer as the MD to not be identified as the drug pusher, and let people buy their product of choice without my input. 
Let them take a course just like we do with firearms and cars, and when they pass, let them make the choice on their own. One certificate for narcotics, another for ketamine, etc.