Something like Bangaa or any bestial race like the werewolves people would post in the past or some other strange ideas would never work because of the Ceremony of Eternal Bonding.

Try to imagine how a Bangaa and an Au Ra female would go through the Ceremony of Eternal Bonding: The Lover's Kiss

And they can't give a race exclusive ceremony because then everyone would want one for their race.

SE dug themselves in a hole. I can only imagine Viera or mixed races getting in.