As I recall, another "nope-nope-nope" in the attitude of the Devs is "genitalia art" in skins. Yeah, you can still do it, but with the current resolution it is by default "pixelated out." For every doubling of the resolution, you quadruple the odds of idiots flaunting the size of their avatar's gonads. And since parents can't go after some random kid with tan-elephant head undies, Mojang will have to bear the brunt of the parental annoyance.
Given they've already enough on their plate, Mojang isn't going to do this.
Now there were mods for "HDR Avatars", but last I looked they have been discontinued. https://minelittlepony-mod.com/ As far as I know, the MLP mod is still active and supports "HDR Pony" skins. But I don't think it likely that any higher resolution player skins is going to be a "thing". Anyone offering to support HDR skins is going to be held liable in a court of law for distributing pornography, and it is unlikely anyone with the *means* to mod it in will do so without consulting a lawyer telling them, "Aw hell no!"
So while I like the idea, and I'd really love to have ANY better resolution skin for my ferret avatar, it is unfortunate people suck and make nice things impossible.
I definitely agree with your statement, people do suck and do make nice things impossible a lot of the time.
If higher resolution skins were enabled, as you said and you're right about this, there will be ignorant people who will keep producing or using hentai skins. Low resolution textures helps mask some of this, although it's still not perfect. Then you have a different case, copyright infringement when people use non official avatars that are based on other people's work. It's one of the reasons I chose to use a Microsoft store based skin instead in bedrock edition. While free skins are allowed to be used in either version of Minecraft, fanart skins are not exactly legal.
This is not Mojang's fault at all, while I have disagreed with many of their decisions over the years, I'm afraid they're in the right on this one. They do have a good reason to be concerned when people misuse the ability to use skins with inappropriate content.
Perhaps Microsoft were onto something when they decided to make texture packs and skins a form of microtransaction in Windows 10 edition, using official skins and texture packs you can avoid getting into trouble for use of inappropriate content, and it probably is better if only these ones were allowed, as inconvenient as it sounds for many people, unfortunately too many people abuse their privileges, children and adults, so a company does need to step in and add in a filter of some kind.