i think most of the time 'political correctness' is just treating people how you'd like to be treated - with kindness and respect.
i do agree that perhaps attacking lack of political correctness as a kind of 'ultimate sin' is quite common at the moment, and personally i think if you use slurs or deliberately make people uncomfortable that's probably just being a bad person, and shouldn't necessarily be demonised just for a failure to meet standards of political correctness. but when you're talking about systematic oppression sometimes it's helpful to have parameters for what is considerate to say, especially when it's hard to put yourself in the position of another person.
if a friend asks you to call them nick instead of nicholas its not really a problem, so why is he instead of she?