Jung was famously sceptical of psychedelics, telling people to "beware of unearned knowledge". I think he might have a point, especially considering how much human culture dating back to our earliest records apparently warns of the same thing. The Tree of the Knowledge of Good and Evil, Pandora's Box etc, the idea crops up everywhere.

I certainly don't think we should have the destructive, Puritan regime of prohibition in place (it was pretty much an excuse to arrest members of the left-wing counterculture in the 1960s rather than any genuine public health concern), but completely heading in the other direction isn't a good idea either. The cultures that have used psychedelics for millenia have lots of cultural/spiritual practices around them to make them safer, just taking a pill and thinking you're ready to meet God without any sort of preparation is a recipe for going spectacularly mad.