Infinite Stratos' reason for a female-dominant society was a stupid one. Why would someone even consider investing government funds into manufacturing and mass-producing a space exploration/combat suit designed to function only when being piloted by a female in the first place? Why not both sexes? It doesn't make any sense.
Now that's not to say a female-dominated society is totally unrealistic. Far from it actually. Human genetics continue to change and mutate slowly over time. It won't happen in our lifetime, but perhaps a couple hundreds of thousands of years from now partially in thanks to the degeneration of the Y chromosome, the human male will be practically scarce and unneeded for reproduction. (And btw, this doesn't necessarily mean the entire female population will begin to resort to lesbianism when it happens. Even if the body changes, it doesn't always affect our minds.)
As a guy, it is indeed depressing to think about. I'm just glad I'll be long dead before it happens.
