Reine, I do love that you're so civilized about things. Basically for me, I believe categorizing things doesn't really help people be any bit more true to themselves than letting them be free. Whoever you are attracted to, you're attracted to.
I do get what you're wanting to get at, that unless you're truly transgendered (which I would lean to being), that it's simply a homosexual relationship and they should just accept reality.
Well, the problem with that (and this is why categories are bad) is that there's this sort of typical boy-boy, masculine-masculine (even if one is a bit effeminite) gay model that someone who is a crossdresser cannot relate to. And, it's true, most gay relationships, even those who are here, their partners are NOT keen on any of the feminine aspects of them, whatsoever. They "tolerate" it, but they don't like it, at all. It's these sexuality roles which makes those here consider it something else (which it is, in a way). Now, if the umbrella of homosexuality did include it, then I believe this debate wouldn't even exist.
But, when's the last time you've seen a gay man being happy with his boyfriend always in drag? Absolutely never. When is the last time you've seen a CD attracted to men meet a man who identifies as gay in a gay environment and have a relationship with him? Never.
And, it's not going to change, since this sexual identity role is at the heart of the tolerance that is finally going through society for gay and lesbian couples. There's a sort of "wholesome middle america" package that's brought about, which has pretty much zero wiggle room for a CD and masculine male being together in it. So, people can't identify.
Is this a bit clearer?
Example of this "wholesome middle america" thing I'm talking about:
Edit: I should note that I actually love the "wholesome middle america" thing that is going on (and has always been here), but the answer to me is not to deconstruct it, but just let people be free on how they are if they fall outside of it.
As time will pass, and as this becomes known everywhere as just "normal" you'll get trans women and cis male relationships being seen as more "normal", and given even more time, then you'll be able to have the CD/male dynamic as not seen as just another relationship, and then nothing will matter. In the meantime, people should just be who they are, true to their feelings and not concern themselves about categories (if it was up to me).