The risks are too high.
Informed consent is biologically impossible.
One can't grasp, in advance, the nature of the sorts of experience to which one is nominally consenting. Yet in consequence of this taboo, unimaginably alien state spaces of consciousness remain off-limits to most of us. Trapped in the squalid psychochemical ghetto of Darwinian life, we lack the necessary wetware to conceptualise radically altered states of mind. Yet when the vertebrate genome is rewritten, and genetically-preprogrammed bliss becomes the norm of mental health, our veil of ignorance can be safely ripped aside. Armed with exquisite designer-drugs, even the most outlandish realms of psychedelia can then be investigated in depth.