>>383072652
Besides what others have said (big uncompressed textures and masks on every mesh) there's also the fact that people insists on having 5+ outfits on a single avatar which means even more textures and polys. I've seen ridiculously indulgent bullshit like fancy nails that were like 10 materials ALONE or hair with more bones than my entire model. 

And you know what the worst part is? It's not even that people don't care, they just don't know. You complain to them about avatar stats and they have no idea what the hell are you talking about and how it works. Using autodresser in Unity and maybe a simple texture edit in PS/GIMP is the height of work lots of people are willing to do when it comes to avatars.