But in service to our project, I re-read "Celephaïs" and found that it makes a whole lot more sense, or is at least a whole lot more fun, if you treat Ooth-Nargai, et al., as Faërie. Then, it's the fairly creepy (not least because quasi-sympathetic) story of a man seduced by the Other Side, not a mawkish exercise in artistic self-pity and whining. Indeed, read thusly, it merits comparison with Machen's "The White People," which is not something I would have thought remotely plausible before now.
That said, I think HPL intended it to be artistic criticism as much as anything, and it fails at that resoundingly, not least because the story doesn't actually obey its own dictates, striving far too clumsily for effect rather than acheiving effortless transmission of antique beauty. But again, it was a very early, very amateurish effort.