Female/black leads and diverse casts have been considered politically correct for decades. The only difference is political correctness is more controversial than it was in the 90s, probably because some shows (Voyager included) neglected quality stories and the only thing going for them was being politically correct. So now the idea is if a show is overtly-politically-correct, the storytelling will suffer for it. Problem is, a lot of the time, it’s true.
Shit’s just lazy writing. You see it everywhere. Any time themes are too heavy handed/on the nose without much else of substance the storytelling suffers for it. But what the themes are shouldn’t matter. Blame the writers, not political correctness.