Tusks and fangs (respectively) for head slots. It would give people room to shift say, roegadyn into orcs, make ogres or trolls of sorts, get some vampires, edge au ra into more demonic territory, or just have teeth like keepers of the moon. It's a little thing but might open designs up a bunch.
Dyeable beards and mustaches, or just more beads and mustaches in character creator. Similar reason to tusks/fangs, this could make more flexibility in terms of character design. Might be fun to make a lalafell look like a more conventional dwarf.
Antlers that are not made from cloth, preferably ones that are relatively thin and sharp. Related, foot gear that makes it look like you have more realistic cloven hooves than the reindeer set. Hooves might be fun paired with au ra for (again) a more demonic vibe.
Flamenco dancer-inspired gear for dancers.
A really blinged out caster hat, like with brass bits as the main decoration instead of feathers or even jewels but still having the classic wizard shape.
Dyable Ivalician Oracle's Coat.
A fully dyable turban for casters that doesn't mask the face and only uses neutral colors as accents (if any).
Something like a male version of the Oasis Sarouel from the Gold Saucer. As a caster, right now the closest thing seems to be Replica Dreadwyrm Tonban of Casting and it's pricey.
Ascian-style gauntlets, clawed gauntlets in-general.
Simple, fully dyable hoods that don't completely obscure hair and don't have big brown patches like the rain gear set.
Amaurotine masks.
Amaurotine robes.
Gear modeled after the Twelve, or at least weapon sets.
Warring Triad glamour, similar in feel to the weapons.