Because there is a difference between you seeing the story from the perspective of a pre-estabilished character you have no control over (Fran) versus having the freedom to fully customize your character and playing it according to your judgement.
A lot of people are using the whole "But Final Fantasy XII don't have male Viera" argument and forgetting that the only reason that's the case is because apart from Bangaa, every other race that isn't a human on XII is close to not existing. We haven't seen female Garifs or Revs just as much as we haven't seen male Vieras, and that's because the stry telling of the game didn't find it necessary to introduce them just because.
However that is the complete opposite of an implementetion of the race on a multiplayer create-your-own-character fantasy game. Yes, we had Mithra and Galka being gender locked, but please take into consideration that there's a difference between a game that is already designed to have that feature from day 0 and a game that started with the idea of every race being able to have both genders.
I wouldn't classify this as "social justice warrior", and I'm curious to know if all the people with those arguments -weirdly enough all coming from female character players- would still be all "that's how's supposed to be" if there was only a male race option to be talked about on the matter.
