It came to my mind if we have equally solid research for the effectivity of drugs like antidepressants. They have fame of sometimes working and sometimes don't depending on the patient, and I guess the same could be said of many psychedelics.
I'm not at all against antidepressants, and I know several people who have been helped a lot by them. But if there are potential alternatives like ketamine and psychedelics that have lower risk of side effects (ketamine in particular is extremely safe taken in a therapeutic setting) and only need to be taken once to potentially see an immediate effect, even if the science is weak, shouldn't these at least be available for adults to try before putting them on antidepressants?
And my memory of reading up on this is that the current understanding of how ketamine works for treating depression is that it's something about the way the body processes & gets rid of the ketamine, it's not from the effects that the person taking it feels (unlike with psychedelics where it's the effects themselves that open up new neural pathways in the brain allowing therapy to potentially be more effective). And taking ketamine daily won't be more effective for treating depression. So I wouldn't expect many patients to go from the medical treatment to thinking "I want to start using this recreationally" (though if enough people get treated with it, of course a few people are bound to go down that path - but plenty of people already go down the path of choosing to use it for fun).
Empirical research is also research.
That said, I agree. We need more research, which would have happened a long time ago if it wasn't for criminalization.
The same could be said for almost any drug or intervention.