Lore outside of this game doesn't hold inside this game. We've said that countless times before. These Viera are not the Viera of FFXII/TA/TA2. Other PCs may as well be Default Male Midlanders since the game never treats them as anything, and the handful of times when other adventurers are even mentioned it's mostly tongue-in-cheek from the EN localization team, as those references aren't in the JP version.

Male Viera exist in this game, Male Viera are mentioned several times in this game (as are Female Hrothgar, even more than M!Viera), for the missing genders to become playable it wouldn't actually break any lore rules unless an avalanche of NPCs showed up, and even if/when those NPCs show up they'll more than likely offer some Lore Excuse as to how they're suddenly there (e.g. Queen Gunhildr, a random Viera needing assistance, what have you).

Also, I know this is petty but the "erp fodder" comment is rich coming from someone with THE more popular race/gender combo for erp.