Language changes, of course, as it is a protean tool of the living. Words may change meaning, sometimes dramatically, over the course of just one generation. Institutions, especially the church and the academy, often change the meanings of words in order to distract from their failure to address their decline in influence in a diverse society. These changes eventually percolate into general usage.
In observing the current presidential election cycle, I've noticed that the definition of "politically correct" has now shifted. Whereas it once related to the tedious practice of policing one's words and thoughts in order to conform to the view of the self-righteous minority who control politics, entertainment, and the media, it now seems to have something to do with common dignity and what my grandmother would have called "good manners".
Recently, while at the barber shop, another patron was complimenting the work of the loud, orange fellow whose whim it is to be our nation's president. He told me that he loved that the candidate-to-be was "not politically correct" and cited as evidence the occasions when Orange Julius Caesar called people insulting names, engaged in vulgar commentary, and generally behaved like the pugnacious drunk at a wedding reception who is on the verge of emesis [in my profession, I've seen my share of those].
In short, to be "politically correct" nowadays means to have the comportment of a sentient, emotionally mature, and mentally able adult. To be "politically incorrect" means to mimic the behavior of an abrasive inebriate. That's quite a change, and not for the best if society is to maintain at least the skeletal structure of civility.