I think you need to remember to look at psychedelics from the perspective of someone who's as devoutly materialistic as a lot of these atheists are. From that perspective, we psychedelic enthusiasts probably don't look any different from people who drink alcohol for pleasure and get plastered. We're altering our consciousness for some kind of 'high.'
It's the nature of this particular compound that it flips the cognitive switches associated with 'profundity,' and so we lap it up, even though (again, from their perspective) we're just giving ourselves cases of drug-induced psychosis.
I think this gives insight into prohibitionist mindsets too.
It's like a lot of Nexians look down on those who consume alcohol, or how I'm sure most of us would look askance at anyone who said 'hey, the shadow people I met after my 5 day meth binge have bee really insightful, wanna try?'
Blessings
~ND
"There are many paths up the same mountain."