1000% behind this! here's my own personal wishlist for expanded character personalization:

1) wider variety of heterochromia options. currently we can only do odd eyes (I think it's finally been expanded beyond miqo now to be universal?), but there's so many different types of heterochromia, like inner/outer ring and variegated! plus, there's even at least one npc in Dawntrail (Yanna) with non-odd eye heterochromia (green upper irises and yellow bottom irises) so I feel like this could definitely be a possibility in the future.

2) additional tattoo options, not only for the face but for the body as well. I know body tattoos might be a tough ask since there's a lot of armor that comes with tattoos as part of the design, but I'd still like the option even if it ends up clashing!

3) de-couple the scar options from the face types and make them universal across all races/subraces/genders! of all things to be restricted by face type/race/gender, scars are the genuinely the most baffling to me. like, are the facial wounds gendered now?? c'mon.

4) additional ear/horn variations. plenty of other people have mentioned examples in this thread, but my personal most wanted feature for this would be more miqo ear variety in particular. we don't get ear shape/length options like viera/elezen do (and probs won't bc we all know how SE is with hats), so I would at least want something like black-tipped ears, chipped ears, striped or spotted fur patterns, etc.

5) let the sun miqo have the moon miqo teeth!! actually, in fact just let everyone have the teeth. we should all get to have fangs if we want.