The rise of 'telling it like it is' anti-PC commentary (on the right-wing and in atheist circles, e.g.) is surely connected to the erosion of certainties which increased knowledge (i.e. research, education) and empathy is forcing us to acknowledge and accept.
(Actually, I think this is one of Zizek's hobby horses: the revolt against 'common sense' and simple explanations, to the extent that he is moved (in mind and gesticulating body) to ask questions like 'what if Stalin was good?' I mean this is sort of the foundation of 'cultural theory', isn't it? Deconstructionism, Freudianism. Not telling it like it is, but telling us what it isn't.)
Anyway, that same fear (coupled with homophobia, of course) is aroused in transphobia, in the idea that 'a man is a man, a woman is a woman, a spade is a spade'.
Puts me in mind of the dual-mind theory (as written about in 'Thinking Fast and Slow'): the mental mechanism which predisposes us towards easy answers.
Perhaps also the internet has a role here? The profusion of unverified knowledge, theories and facts makes people long for a loud, confident voice to tell them 'ignore all this other shit, listen to ME.'
oh, and it should go without saying that white, straight males have inherited a 'common sense' invented for the most part by white, straight males, 'common sense' which of course privileges them and their values above everybody else, and so they're horrified to see that privilege being eroded along with their certainties. I think I feel this way too, without wishing to. I certainly feel impatience with certain aspects of the social justice movement, but perhaps that's just me unconsciously thinking 'the world seems alright TO ME, why complain about it?'