For most of the general public, the most common frame of reference for crossdressing is the Drag Queen circuit which has been predominantly a subset of the gay community. Thus the immediate mental association of crossdressing and gay.
The differentiation between Gender Identity and Sexual orientation is difficult for most to grasp. (Count the number of posts from new members that incluse "Am I.. or Is he.. gay?").
With more acceptance and more openness, the difference will come out. Differentiation is a good thing, but acceptance is higher on the list IMHO. I someone accepts me I can explain the difference. If they do not accept me I probably will not get the chance. I would rather piggyback on a law that prohibits GBLT discrimination than attempt to seperate GBL from T
