The problem is that "wrong body" fits easily into the pre-existing societal framework, with very clear enabling expectations for what it means.

What you're talking about doesn't. There seems no particular reason a priori that some modest-sized group of people that decides to make arbitrarily large changes to society should be allowed to do it over the objections of others. There certainly are objections. So it takes a lot of persuasion, if it's going to succeed at all: both good argumentation and good outreach.

In the meantime, people for whom "wrong body" is a pretty good approximation get thrown under the bus, because society is moderately willing to accept them, but not necessarily trans political philosophy and the transfeminist manifesto, and if it seems like an all-or-nothing proposition (or like there isn't even any distinction), a lot of people choose "nothing".