I'm glad you think so since that's exactly the approach I've taken in both the games mentioned, and only partly because it involves less drawing ;)

We discussed choosing ethnicity for the second game but the main character's backstory is too rooted in their family history, especially their father's family being Bengali. They're also always visibly disabled, which again is a part of their backstory and affects how people relate to them. Their variable gender and presentation affect how people react too, if only in minor ways, but that's the kind of thing it's fun to vary in multiple playthroughs of a dating sim, and is also pretty easy to keep track of. Their body type isn't going to affect gameplay, it's just to help players with the roleplaying aspect.

I don't think I've ever seen a game let you choose you character's ethnicity and have it actually change anything in the game (not counting being an elf etc). I can think of a few ways you might plausibly be able to implement it but feel unqualified to decide which would be best.