Why I Play Who I Play
Okay, so I'm a guy and I've played at least three or four female PCs in my time. Different campaigns and such.
Why?
Because I was interested in them.
I note that nobody has talked about characters as people they're interested in. That's 100% why I play who I play. I want to see how these people behave, if they can overcome their issues or perils or whatever. Will Fred ever find his little sister and if he does, what will happen to his adventuring lifestyle? Will Jill ever track down the gnolls who decimated her village, including her father who she idolized?
I CARE about my characters. They MATTER to me. I LIKE them. I play them to, as much as anything, find out what happens to them. Because I'm worried about them. I want them to have happy endings.
Whether they're male or female doesn't really signify to me, except insofar as they possess a gender when they come to me. I play them whatever gender they are.
As far as DM's restricting character choices, while I have to admit, Snoweel, your style of communication seems a little more confrontational than is really necessary, I have a very similar system to you -- humans only, fighters and rogues only. Players have to make very detailed cases to play anything else, and whatever happens I usually twist the class around to fit my campaign's rather peculiar cosmology and magic system.
A DM can do whatever they want with their campaign. I don't think that any way is conclusively BETTER than any other, and if my system hugely sucks I'll probably have trouble finding players. Which I kinda do, so perhaps I suck. But I have every right to suck if I want to.
As far as T Billy's system goes, I've never had to implement anything that drastic, fortunately, and I have to say that to me it speaks much more highly of the maturity of the people he's played with than any general statement on mankind. Which he was the first to point out, of course.
The idea that guys who play women are actually playing transvestities is hilarious, though. It's like saying guys who play fighters are actually playing VirtuaFighter players. No. When I play a female character, I'm playing a woman. I may be doing a poor job of it, but that's what I'm doing. When I play a transvestite, THAT'S when I'm playing a transvestite.