It is rather interesting the number of cultures who have their "best" visions right after taking a hallucinogen...
True.
Also there is an aspect to this not widely realised which I have learned directly, and that is that some skill can be developed in these inner realms. And it is not a pointless skill, nor need it relate to 'religious' ideas.
Psychiatrists and their more effectively treated clients can attest to the fact that some medications will cause improvements in some aspects of functioning, and these improvements remain after cessation of medication. I can give examples of what I mean if you want, but the gist of it is - the brain physically changes.
Tibetan Buddhist practices involve detailed visualization, and I can attest to the fact that these skills do not require drugs.
As for the uses of these skills, there are various which I can report from experience. One is in my primary artistic activity. Generally people are at least aware that there is some faculty of visualisation in any normal brain. Dreaming makes that obvious. Plenty of visual artists clearly imagine what they subsequently produce. I can now 'audialise' very clearly, which as a musician I appreciate muchly. And occasionally I enjoy simply listening to spontaneous music.
Then there are the social applications. In central America there have been (are still I trust) cultures where 'family therapy' involved a shaman using psilocybe mushrooms in the company of the family, and subsequent 'visions' effectively symbolically communicate the situation and it's resolution.
I guess what I am saying is that it is adding or enhancing an innate faculty to the collection of skills a human can develop.
How and why this is so controversial, politically and religiously is a whole other topic ...