I wouldn't mind seeing Viera in game. However lore wise from the games that took place in Ivalice "FFTA, FFTA2, FFXII" only had female Viera in them. While this could easily be resolved through storytelling it seems like SE wanted to stay away from making races gender exclusive as back in FFXI Mithra which Miqote were based on were female only and Galka which roes were based off of were male only.
Ivalice also gave us the races of Bangaa, Nu Mou, Seeq, and Gria while also having playable moogles that were probably size wise about on par with a lalafel and didn't fly.