Seriously, I just want to read about horseys doing horsey things, and all I get is a bunch of harem self-insert fics.

5557167
Well, I think the majority of the interest in the subject is not necessarily in the subject itself, per se, but rather in the juxtaposition of a nominally patriarchal social norm with the matriarchal social norm and the similarities and the differences between the two as well as the clashes and their resolutions. The comedic and drama possibilities are high.

That and, for many, writing these things is a bit of a fantasy escapist wish fulfillment. Write what you like and/or want to read and all that jazz.

5558885
Ditto. Could not have put it better myself.

I have to agree in that a lot of herd stories involve humans. However, I've also found that while there can be a lot of pony-on-human sex, there's also some damn good world building going on. I don't know why but it does seem that (some) clop seems to bring out some good writers.

Just recently I dug into the Gentlemanverse and the Xenophilia-verse. Yes, both involve sex, but both involve herd dynamics and lots of sociopolitical issues that I find amazing.

However, I will say that there's a hell of lot of crap out there as well, but when you find the diamonds, oh, how they shine. (And I don't just mean the ones on Rarity's flank. )