It's because it's already about trannies and it's not cool or popular. They don't want their own thing, they want our things. They don't want a series about like a trans super hero, they want Spiderman to be trans and it has to be Pete Parker. We can't have an anime about trans, it has to be Luffy or something. We have to change everything to fit their needs because they're mentally undeveloped children who need everything to include their new interest and/or hobby.
You know, this makes me wonder why troons aren't all over F-Compo, by Tsukasa Hojo. It's a manga about a young man who, after the death of both his parents, is taken into his uncle's house, to live with his family. But, how bizarre, it's his aunt who is the spitting copy of his mother. Later he learns that his aunt is male (he's his mother's brother), while his uncle is female. They both pass perfectly, of course, all the transpeople in this comic pass perfectly without surgery or other medical treatments (the transwoman is non-op, the transman still menstruates), except for one of the uncle's assistants who is the stereotype of the non-passing masculine troon put there as a comic relief.
Anyway the couple lives a perfectly normal life (the 'husband' draws manga, the 'wife' is the perfect housewife), they even have a daughter...but will she be really female? I mean, this is the typical kind of story troons would cream their pants on. Strange that I don't see it promoted in troons circles.