>Has any thought been given to adding more gender_only stuff?

Why should the stuff be gender only? It would need a good anathomical reason. Otherwise the flag would be plain stupid.

>Sirine island has a lot of female_only stuff, but what about
>male_only stuff?

Maybe, or remove the female only flag from items in which it makes no sense. Genders should be equally viable pick so that people wouldn't pick their gender for powerplaying reasons.

>What about a male_only/female_only class

Why would the class be male/female only.

>or a female_only race?

Maybe some kind of a dryad.

>Or do you think it would add an unwanted note of discrimination to the game?

Discrimination is unwanted because it encourages powerplay picking in character creation.