To fit in.
I would prefer to be myself and wear the clothes I find comfortable and appropriate for the situation, but in my real world, that does not work. I can not have a short hair cut, a moustache, wear a dress and use my male name. I can either, not wear some of the clothes I like or I can shave, wear a wig, makeup, a dress and femme style shoes.
When I found this forum, read many posts and got an idea of what this world was all about and wanted to register and add my 5 cents worth, I decided to follow the trend and choose a femme name.
I may get boo hoo'd down, but in my real world, you can not be a man wearing a dress, but you can be a man trying to pass as a woman....
Each to their own I guess.