Try mentally tabooing the word "medical" and review your positions on medical marijuana. My impression here is that you have strong cached thoughts about what does and does not qualify as "medical", and the difference between medical and non-medical reasons isn't as large as you think. For one hypothetical example, if there was a drug that made average people into geniuses, would its use qualify as "medical", or "performance enhancing"? What about a drug that made below-average people average? What's the difference, except expectations about what constitutes normality?

Maybe, but what would you recommend instead? The usual painkillers are more addictive, have worse side effects (which is why they cannot be used as frequently as the patients would need), and they also get stolen by people working in medicine for recreational purposes.