Beyond its novelty, there are obvious reasons for that stark unpopularity: When spoken, “Latinx” sounds like neither normal English nor conversational Spanish, and it looks like what it is, a word designed for ideological purposes rather than for felicity in speech. If you are deep inside progressive discourse, you will immediately understand those purposes — “dismantling the default masculine” of romance languages, centering gender neutrality or nonbinariness in place of a cisgender heteronormativity. If you are outside that discourse, politicians who use it will sound like they don’t know how to say “Latino,” or like they’re talking to an audience that doesn’t really include you.
Which, for a politician, seems like a bit of a problem. One of the common defenses of political correctness is that it’s just a synonym for politeness, for calling people what they themselves want to be called and showing sensitivity to minority experiences and burdens that men or white people don’t share. Which is sometimes true: The example of white people whining that they don’t get to say the “N-word,” for instance, shows how anti-P.C. sentiment can sometimes reflect a desire to ignore history and flip common decency the bird.
But just as often the language of P.C. has more to do with imposing elite norms of discourse on a wider population that neither necessarily wants them nor fully understands their purpose.