PC Culture has a down side. Its all great and warm and fuzzy to look out for peoples feelings, but unfortunately this idea can be used (intentionally or otherwise) to justify social intolerance of all kinds of disagreement and thus become a tool for dogmatic ideological control of society. I think this is what we are seeing happening in many places.
Liberalism and progressiveness should be about TOLERANCE. Tolerance means to be willing to endure the existence of, and exposure to, what you dislike.
I am not referring specifically to the changing of the words in the song, but just the slippery slope of oversensitive PC culture. Hell, hardly anything is funny anymore! Partly because the truth can be both offensive and funny.