Oh my - Phoenix, you have made my day! Yours was a fantastic OP! Subsequent offerings have been wonderful and - perhaps more importantly - the exchanges between us fantastic! This is an amazing thread! I appreciate this so much, I am NOT going to offer you a +1!
But I will try to slip my own two cents onto the table:
Though I have throughout my life outwardly appeared male to the world, my inner sense of body, spirit, and mind leans more toward female. This situation fluctuates over time, but the preceding generally summarizes my experience.
Because of this, I have been perceived as male, treated as male, socialized as male, and privileged as male. Much of this I have not liked. Much of this has never 'fit'. Much of this I have denied, ignored, and/or resisted. Much of this has hurt and confused and angered me deeply.
Given a choice, I would have elected to be perceived as female, treated as female, socialized as female, and privileged as female. But this truth is, I wasn't. I was perceived, treated, socialized, and privileged male. In spite of any inner sense I might have, in spite of any yearnings or preferences I might feel, this fact has deeply and profoundly shaped the person I am. Even if I were able to snap my fingers right now and become 100% bodily female, I feel I would not be the 'equivalent' of a cis female by virtue of this fact.
This situation frequently depresses me and I have given this a great deal of consideration. To cut a long story short, I have come to believe the foundational source of this depression is the issue of legitimacy. Our culture legitimizes only two genders: male and female. One is either a man or a woman, and that's about it. If one does not 'fit' within this schema, if this polar conception of gender does not work for some people, well it remains the only game in town - so such folk are very much out of luck! Put another way, such folk are left socially illegitimate - not really seen or acknowledged, not really granted a 'place' in the prevailing order.
Somewhat surprisingly, in spite of the fact this way of thinking leaves so many of its own people out/unacknowledged, the trans community seems, for the most part, to function under this very same binary umbrella. Hence, in my opinion, the recurring debates about 'real' men and women - debates that, from this perspective, are not really about gender, but instead express much deeper concerns about legitimacy, about having a socially sanctioned place. Such debates, then, are about our very existence! About our ability to say, 'I'm here!' and be recognized/seen in doing so. This, perhaps, explains why these exchanges can become so very heated!
All this said, then, perhaps our greatest - and most fruitful - challenge as trans folk lay not in the 'real' debates, but in finding ways to socially legitimize a broader range of gender experience. So that people like myself can say, 'Well, I'm not a cis man and I'm not a cis woman, but I am a ______' So that the world around me can hear my words, nod its head, and open it's arms wide in welcome.