Speaking from the perspective of a bisexual:
You have to remember that the door is open as the phrase is Lesbian Gay Bisexual Transgendered, However, it seems than MANY crossdressers don't view themselves as transgendered. The thought process seems to be folks think of themselves as genetic heterosexual males who just happen to like women's clothes. While I respect that and would not challenge it, I do wonder about it because it is easy to feel no alignment with LGBT folks. I suspect it would be better for all concerned if crossdressers did consider themselves part of the community. As long as various factions of the community are separated, it is much more difficult to move forward and gain acceptance and respect.