Two major patches and Mi'qote female STILL don't get sideshave and dreadlocks?

[Lillia]

In that case, it's simply styles that were seen as exclusive to certain races (or they couldn't make it work with certain races)

Dreads won't be added till 2.4 though, every new hairstyle exclusive to one race isn't open till the next major patch. So..... that doesn't really apply as the reason for no dreads yet.

[Felis]

Can we just convert to F2P and make a cash shop solely full of vanity for endless amusement?

Only if you want to pay for items only once and not anymore because it would count as account wide bonus items
Vanity is good.
Vanity don't mean F2P.
ARR is not the only P2P game with different hairstyles and different gear models with the ability to change hairstyle and gear without buying them.

[Shioban]

Dreads won't be added till 2.4 though, every new hairstyle exclusive to one race isn't open till the next major patch. So..... that doesn't really apply as the reason for no dreads yet.

Not the dreads specifically, but I can see problems occurring for adjusting the "skrillex" hair for Female Miqo'tes.