Respect and politeness are crucial in constructive debate. If offensive language is condoned in the media and in our society, then ideas polarise very quickly and risk turning violent. If debate is not respectful then there is no point in it. The point of discussion is learning from one another. Without respect, the argument becomes two people trying to validate their opinion without being openminded. If we are not openminded we cannot function in a democracy.
Political correctness doesn’t stop controversial ideas turning violent - censorship does. Political correctness merely softens the language used to express ideas, which in effect is not very significant