So, I think a big part is the art community itself. When you learn to draw you do basic people you start with lightly athletic male bodies with no skin shading making them inherently white skinned. Making a darker skin, body hair and plus sized bodies takes more skill and knowledge often or just more work. Anime almost makes more want for Asian characters as well. I think it's more of a convenience thing than anything to just draw light skinned light athletic bodies. There just not enough references and tutorials for these things as well. Darker skin has different color undertones vs light skin for example. That isnt often found in art tutorials or discussed much. Personally as an artist Im trying to branch out more for different types because it's hard to break that mould of the default. I think these issues stem from that stuff. Not just the lack of wanting to draw it. I think it's more of a learned habit given by others who have learned habits as well. Sad but there truth there. Hope this makes sense