LogFAQs > #978731486

I personally believe its because the ponies are cute. A similar phenomenon is seen in Pokemon with the eeveelutions in which theyre considered attractive despite being quadruped creatures .

https://gamefaqs.gamespot.com/a/forum/9/98aeaf5d.jpg

Another poll, Pokesmash, which is heavily used by streamers, is aimed at a general audience and has a sample size of over half a million, has Vaporeon, Ninetales and Sylveon beat every Pokemon in smash percent except for Gardevoir, Lopunny, Zoroark and Delphox. I see it more as in being cute washes away any shame on these characters being quadruped in shape, much like the eeveelutions the mlp ponies are heavily inspired by kawaii anime designs.