I love this! I'm using your Tileset on my private workadventure server, and I'm looking forward to integrating an avatar creator!
This system is also a great way to easily increase diversity in characters. Just by adding, say, a headscarf, turban and white cane you could already make a bunch of characters from underrepresented groups. A wheelchair would be incredible, but also probably difficult with the way the animations work.
What I really like is that options are not separated by gender. You can make some feminine or masculine characters, but also lots of ambiguous ones. Just a few more skirt/dress outfits and weird hair colors would be nice.
And I know you're not in the "add lots of stuff" phase of this project yet. It just seems like you appreciate ideas, and I'm getting a bit hyped ;)