What if the reason why there isn't a new race is because...

[The_Last_Dragoon]

Hybrid race options don't really make sense lore wise. Hybrids aren't impossible obviously (although some combinations probably are) but they are extremely rare, rare to the point that we've only met one after traveling all over Eorzea.
A thousand hybrids suddenly appearing in Limsa would be silly.

It could be funny if it was explained away lore-wise as a "fad where people mess with their genetic make-up using a strange potion in order to make outlandish combinations of the races."

I mean, it's not like this sort of thing doesn't happen in Japan...