the general reason was was it was too similar to miqo'te to add in the game ....

lets take a step back and look at that . is it a real reason? does it mean anything at all? whats similar whats not?

for this the 1st thing i instantly did after seeing that was count the similar to the not in retrospect to all the races . sounds like alot but it only took like a second .

ok miqo'te to viera how their similar : both are animal variations ... to that end both elezan and rygoden are hyur variations and au rah is another animal variation..... so...no that reason does not stand.

if its physical differences needed then lets look : How they differ : fore arm length neck length , general hight , tail type,ear type,eyes, facial features and foot size& shape.

they seem to have more not in common then in common ...