Hairstlyes no one talks about

[Silverbane]

I was massively disappointed when I saw neither the Omega suit came with the hairstyle nor the Ryne costume. That makes me feel like we might never see those hairs in game.

There may be good reasons for that, reasons why we also won't see Shiva's either, if the following hypothesis is true:
Many NPCs may be just character-creation system products, but quite a lot of them may effectively be monsters: full custom creations with intrinsic costuming and hair and custom rigging for the costume and hair physics. And they might be way more complicated than PCs, complicated to the level that putting a score of them in the Limsa Lominsa Aetheryte Plaza would reduce most player's frame rate substantially.

If I'm right,
we'll never have Shiva's hair because it isn't really hair the way hair is for PCs.
And we'll never have her outfit because it isn't an outfit, it's her.
And we'll never have her figure as a character option because it's outside the limits that the existing clothing/armor is designed to accomodate.*

We might get an outfit inspired by Shiva.
Her hair though is probably so outside the limits of the PC hair physics system that even a proper homage to it is off the table.

Now, probably the people who crunch the client database (e.g. Garland tools) can tell you which NPCs are ordinary character models, and which are "beautiful monsters." If a hairstyle or outfit you want is only on the latter, I wouldn't be too optimistic about getting it as a player option.

*and because it would corrupt the morals of the minor males (at a minimum) playing the game.

[Cygnia]

If Krile keeps her hood up/has a haircut in the future I'd be game for obtaining her ponytail...even though we have a fair number of ponytails already available in the game, the one she sports is different enough to stand out.
Also is it me or do we actually have a fair number of longish hairstyles in game? Maybe there's more short and spiky hair overall, but I don't feel like we're hurting so much for long hair as we lack flair in the greater number of hairdos. A flair usually reserved for the handful of racial hairstyles each race has locked behind their selection.

[TheMightyMollusk]

We might get an outfit inspired by Shiva.

The Hailstorm set (level 60 i240 gear for casters and healers, available for Poetics in Ishgard and Idyllshire) is Shiva-inspired, although toned down to fit character model physics.

[Ameela]

I was massively disappointed when I saw neither the Omega suit came with the hairstyle nor the Ryne costume. That makes me feel like we might never see those hairs in game.

I think the devs have talked about how certain NPCs have specific features that they don't want to make available to players as it'd stop them from being unique, like Momodi's hairpin.

[KurohNeko]

Yotsuyu pls

Pretty sure Yoshi would rather commit seppuku than add any hairstyle with actual length beyond the shoulders to the game that we can actually use.

[TabrisOmbrelame]

I think the devs have talked about how certain NPCs have specific features that they don't want to make available to players as it'd stop them from being unique, like Momodi's hairpin.

That is true, just to name a few exemple :

Hildibrand got a unique face (But you can get quite near what he looks like, you will still never be the perfect copy)
Raubahn is Unique
Hilda got unique elf ears + Hairstyle
Y'shtola got a unique face (Again you can't copy her exactly)
Same goes for Thancred, Krile, Estinien (Without helm version), G'raha Tia, Urianger and many other, like Yotsuyu just to name her.

And the list goes on.

Still, their is also plenty of NPC who can be copied perfectly because they are "Generic", such as Godbert and Julian Manderville, Sigurdu, Sadu, Magnai... etc etc...