People need to stop blowing this right the fuck out of proportion.
ON TOPIC, since so many have forgotten it and gone off into tangents: Sexism is bad, people. Your arguments are relevent ONLY when it fits the context! Let's take a role playing game like Dragon Age Origins. Hell, why not World of Warcraft?
This is a game that lets you define YOUR destiny and place YOURSELF into the world. It does not matter if you're a man, woman, black, white, asian, whatever. You make your character to how you like. Therefore, it would be disgustingly offensive if you couldn't make a female character, because you have the option to make the character how you want them to appear and there is equal representation. Fair enough Okay.
Now take a game with a fixed storyline and demographic. A war game, for example. Call of Duty. It's a game based on actual events that, in all honesty, consists primarily of men, when we're talking about frontline foot-grunt soldiers. Not only that, it's a game that primarily and knowingly targets a male audience. Men like guns, they like action and blood and the whole "fight for your country" approach that Americans are so fond of. This is a male environment, with a male demographic, so why the heck wouldn't it cater to simply men? I think a lot of male gamers may, despite the whole "I'm not sexist" argument, be quite up in arms to find out they're being forced to play a character with breasts simply because the game has to remain "politically correct". Maybe they don't want to play as a woman. Alternatively - why should they care? Why should YOU care? Is having breasts on your avatar that bloody important to you? Are you sexist for not wanting to play a man? What's so wrong with us?
You rarely, if ever, see your character in an FPS so stop whining about something that is stupidly arbitrary. And let's not forget the incredible lack of customisation in FPS games. As stated, you don't make your character, you can't customise it, so the option's not going to be there. And as shocking as this may sound to you, i don't really want to hear Master Chief's voice be made into a girl's to make him sound like he's been made into a eunuch for the sake of being PC. Because it just doesn't FIT INTO CONTEXT.
And while i'm on this topic, what about orientals? Homosexuals? Black people, even, to some extent? Where are they? Nowhere, and yet you don't see them crying about it. How many video games can you think of where the main character is gay or lesbian for example? How's that for equality?
Edit: As for why the games industry may 'ignore' women as you claim and focus only on men when they market these games, it's because we live in a democracy, and this even applies to corporations and marketing. They look at the figures and ask "Where does the majority rule? Who will be more likely to buy these games?" the answer is men. So, ruling in the majority's favour, that is where the time effort and money is put. Doesn't make them sexist, it just makes them democratic and smart. I may have a thing for banana and jelly sandwiches, but that doesn't mean my local supermarket is going to stock them. Gasp, discrimination!
