- Skin tones. Doesn't have to include skin tones that you believe don't fit the setting, but even medieval NW europeans had all kinds of white, pink, red, tan and brown complexions.
- More Hair/Beard colors and styles. The same five or six have started to get a little old. Particularly jet black and white/light gray hair, and a few more female hairstyles (eg more types of ponytail, pigtails, free-flowing straight/curly with bangs, etc) since female hearthlings lack the variety beards provide.
- More face expressions. This is a big one, sure Miss Blank Stare and Mister No-Eyebrows Frown are iconic, but being able to choose between a few would mean a lot since the player's face most prominently features in most clothing arrangements. User "Nightdawg" has been tooling with alternate face textures lately, see here.
- Slight variations in Height, which could be as simple as stretching the character model/mesh below the head slightly up/down. Width/thickness/build would probably have to be done more carefully on a per-limb basis but would not be impossible. For now, being able to have diverse character heights would go a long way in them not feeling samey
Might be nice to touch up the character models and existing hairstyles a little bit too (top of head clips thru 'short skew'). Their calves are simply too wide.