Additionaly, though I give psychedelics much credit, if we are going to point to the value and promise of subjective first person research into the nature of the mind, its worth mentioning meditation and mindfulness, another subject area that is widely studied by psychologists, psychiatrists and neuroscientists and is also gaining wide spread adoption clinically, for instance in the treatmentment of depression and anxiety.
Additionally, though both psychadelics and meditation have only really been studied widely in the west recently (you mentioned two generations, might be a bit more) they are both built upon long traditions of study in cultures around the world. I would argue that budhism contains one of the most in depth, analytical and methodological studies of the mind from a direct and subjective first person experience amongst millions of practioners for thousands of years. I am truly inspired by the synergetic results of combining the scientific and emperical tools of science with the considerable knowledge and tools of these traditions.
It seems to me that the biggest problem in tapping into these worlds is that science just doesn't like self reported subjective studies, it really likes to measure things objectively, hence all the brain imaging etc. However, it seems as though with a system as complex as the brain, it might just be that the best tool to measure and understand the mind we have is our own mind. I hope that the scientific pardigm can shift to make use of it.
While in theory AI could have been explored as a science, trying perhaps to simulate human or animal thought processes in hopes of understanding them and perhaps coming up with useful abstractions that could help us reason about them, the field has never really evolved in that direction.