Why are some hair styles race restricted?

[kyuven]

in the case of miqo'te hairstyles, it's because the design is completely different from other races due to the ears.
But in general, the hairstyles have to be designed individually for each race, which takes time. Considering deadlines and how they seem to have a policy of one or two new hairstyles per patch, it's most likely a time constraint thing.
Believe me, it's NOT as simple as sticking a new haircut onto another race. They have to be sized, proportioned, and tested. Moreover, some hairstyles interact with headwear and bodywear. While they seem to have just thrown up their hands when it comes to clipping with some armor, they need to make sure it's not TOO jarring.

[Chiramu]

in the case of miqo'te hairstyles, it's because the design is completely different from other races due to the ears.

Lalafell and Miqo'te share a lot of hair styles so I don't think this is true any more.

[Felis]

Lalafell and Miqo'te share a lot of hair styles so I don't think this is true any more.

Miqo'te got some 1.0 Lalafell hairstyles, but i think it is not the other way.