And really, Hoggkins Law of Planetary Development is some whacky horseshit when you actually think about it. Most people don't think about it, they're just entertained by watching Space Rome, and that's fine, Space Rome was an alright episode. But let's not pretend that by mentioning Hodgkins that episode is more legitimate than a musical which doesn't mention some sort of bogus scientific or sociological theory in order to explain how generating music is possible.
And really, when you get down to it, this whole thing is just a classic case of "if I like it, it's legit, if I don't, it's not." People are okay with the whacky space anomalies and planets that developed parallel to Earth in the other shows because they like the 1966-2005 era of Star Trek while they are down on the musical episode because it's from the modern era, which they will refuse to allow themselves to like. Though at the same time, I'm forced to wonder, if Subspace Rhapsody had been an episode in Picard S3 or even Legacy (if that were a thing), would the same people currently complaining about it instead think of it as the Best Thing Ever and cite it as an example of Lord Terry's "Brilliance"?