I used to jokingly say "dudette" when someone called me dude, but as mentioned, just as a joke because I honestly don't care. I've had, through the years, mostly pleasant experiences and not once have I heard something sexist like I can't play because I'm a girl or anything similar. I don't want anything for free because of my gender because it degrading and I like challenges of trying to achieve it for myself/group/guild.
So I tend to agree, over the internet and in games, gender plays such an unimportant role in the big scheme of things. However, some might be proud or suffer any other unmentioned narcissistic behavior (not judging, just covering all bases) and might want things to be as they are and represented thereafter.
But as long as you're not an *** about it, I don't see the problem because how are we supposed to know to begin with?