It has always been obvious to me that crossdressers are role-playing. Those who are genuinely transgendered will think about it differently but most CDs dress for fun or relaxation. The point of play is to explore new feelings and situations and gain knowledge and experience. That is what we are doing when we cross genders, we stop being ourselves and begin playing at being a girl enjoying and learning along the way.
There are plenty of other examples of role-playing out there eg historical reenactment societies. These people gain similar satisfaction as CDs and they take the role-playing just as seriously. They demand all the details of their costumes and behaviors be as authentic as possible. They want their experience to be realistic because it makes them feel their experience is the same as the character's experience which creates the illusion that we have actually become the character. They even change their name and insist others use it. Sound familiar? They want total immersion as we do. We want to know "what it feels like"
The funny thing is nobody is pushing ideas that historical reenactment players do this because of genetics or hormones since they don't break an important taboo. We can all understand that this behavior stems from 1. a desire to leave behind your real self for a temporary trip into a fantasy and 2. the character we focus on is one which we find fascinating and engaging. We admire specific qualities and want to reproduce them in our play. We become connected to the character and the associated roleplay until it becomes second nature to slip into this alternate personality.