Oh, I can respect how passionate and true he was to his cause. I just think he was completely misguided in how he went about it.
And I also care a lot about realizng the full potential of psychedelics. If they can do more than just help people discover alternative modes of being (like relieving cluster headaches, as you mentioned) then that's fantastic!
The reason we have had dark years isn't because of the absence of good psys either.. It's because, prior to Leary, psychedelic drug use was a personal liberty; however, because of the impact he had on society, we had decades of oppression and legislation aimed at taking away that right. And we are still under these restrictions.
Moreover, I don't know what your comment about a clinical setting has to do with anything.