I think it's killed comedy in many ways.
There could never have been a Richard Pryor in today's climate.
A show like "The Honeymooners" where Jackie Gleason routinely threatened to punch his wife Alice would never fly.
Formerly accepted words such as fat, retarded, midget are now called having curves, mentally challenged, and little people.
More often than not one's utterance of the "wrong word" should be seen as ignorance and not an attempt to intentionally offend anyone.
I can still recall when it was acceptable for African Americans to describe themselves as colored and black . Asians were called Oriental and so on. I'm waiting on the day the homeless will say:
"We're not homeless! We're (Urban Campers)!"
Some folks will always strive to keep up with the latest terminology people prefer and others will stick to what they originally were taught.
This also applies to some things that are considered sexual harassment in the workplace. Several years ago a woman filed a complaint after (overhearing) two male co-workers describe a "Jerry Seinfeld" episode that involved the main characters trying to hold out the longest from masturbating. She was offended and won her lawsuit. A lot of PC is subjective regardless of one's intent.
Now days if one tells a joke they'd better be ready to apologize for offending someone!