Generally speaking, females have a small but increasing place in the gaming community, and it's not because they are excluded or biased against, it's mostly honestly because most of them don't want to be a part of the gaming community. A lot of guys these days DO play video games, and 80% of the time a girl who also lots video games is extremely attractive to a gamer male on that point alone (of course, us being males, a lot of other things come into account...)
I attend Full Sail, most of you have probably heard of this college, and I'm currently in the game design program. There's (and I kid you not) about 1 girl for every 100 guys that attend that degree. That alone says a lot. Most girls are just simply not into video games.
As for guys playing girls, I've heard a lot, and I mean a lot, of excuses. Some I think are valid, some are just bullshit. You hear a lot about guys saying they rather not star at a guy's backside all day. I can go with that, personally I envision myself as my character since I'm big on D&D and rpg's ect, so playing a female character would be... akward.
Some realisticaly picked it for stats, mithra have no male version and a few might of liked their stats and gone with them anyways, since it is after all just a game. There's a lot more reasons, and most of them I'm ok with.. but when it comes down to guys playing like girls, I have a few problems with that.
First of all, unless the male is gay (this is not intended as an offense, I have nothing against gay people) the only logical reason a male would play as a girl is for something wrong. I've seen manthra I know play as the oh so sexually greedy gal to get free stuff. I've seen them do it just to make fun of people, because as I'm sure you all agree getting someone into an online relationship (something else I disagree with) and then halfwaythrough saying "SURPRISE! We're really BOTH guys, hahaha got you!" is SO funny. >.>
Seriously, I can see reasons and have no problem with guys playing girls or girls playing guys. It IS a R.ole P.laying G.ame (RPG smarties). But I think the line is drawn when guys (sorry about being gender specific, the simple fact is not a lot of girls play MMO's) act as girls with another other intent then roleplay or because they are gay.
Honestly I don't see why everyone does the "OOO, a girl" crap in a video game. Cause... well.. it's a video game. WHERE I female, and someone hit on me in a game, I'd straight forward say "sex me, sex me now". Because... I'd die laughing imagining someone humping their screen. (Yes I know about cybering, let's not get into that though. I promise you the gamble goes for 94.3% chance the other "partner" is a guy, which is good or bad depending on weither or not you are a guy,girl, or gay)
Honestly though, the interenet is 80% crap/porn/spam/and other internet evils (that are sometimes pretty good *cough*), 10% assholes, 5% 15 year olds and under, 4% wasted, pointless, purgatory space , and 1% gold. Because it IS possible to suck at the internet. Striking 1% takes skill <.<