Lets be honest: 'This' have 11 pages already and you know why! This is the shadow of our generation, the big untold taboo that no one address and is also exclusive of the internet chats and games. The truth is, 90.5% of you frequently use girls characters as your alter egos, and 9.5% just don't! It is ok! No one cares about it for God sake! The fact is, since the first MMOS males have been playing as majority of the female characters in games. At the beginning, hiding their real gender, but soon (after WoW probably) they started open-up about the subject, although trying not to break character as much as they can. WHAT DOES IT MEANS TO FEEL GOOD BEING YOUR OPPOSITE GENDER? I don't know for sure, but I know you guys are not necessarily homosexuals because of that. This mater is independent of your sexuality orientation. I'm pretty sure of that. What ever your needs are, and why this happen on our modern society it's either a fenomenon caused by the exterior influences of the world around you or a natural human being behavior that could finally flourish within the right environment: online games.
The size of this discussion obviously is because either the majority are still confused about their 'self' as it is, or the minority still don't understand a bit of the fenomenon and because of that have a hard time accepting the fact that your own set of values are not the same as your other peers: society is like this, and one must accept and respect what ever a fellow folks decide to be. Both sides shall respect each other. So, if you play as a female and didn't mentioned your incredible stories to your father, or even your grandfather, maybe it's time to do so. And if you are the blunt minority that have no understanding of other people feelings, remember that it is your duty to accept and respect your peer as they are, no less, no more: Respect be friends. We are all brothers and sisters.
Although you have a point in that the high usage of female characters by men in MMOs is culturally significant, I feel compelled to point out that I don't think it has implications about their gender identity the way you seem to suggest. Only 0.3% of the American population (and roughly that amount of the world population) are transgender, which is to say identify in a gender-nontraditional manner. I would suggest that this has implications more similar to the popularity of My Little Pony amongst 20-something males, which is to say that it reveals that men do, in fact, have a feminine side, and the societal pressure not to reveal that has started to decompose, or at least, will start to do so within the next decade.
I really don't think this is about discovering the truth about men. In my opinion this increase behavior is a result of environment (media is a big one). I can see this in first hand since I came from Brasil to North america and the difference among each nation's men is abysmal. Men is not the same all over the planet and that is for sure.