Political correctness encourages us all to take a closer look at the language we use and ensure that the way we express ourselves is not causing disrespect or offence to a specific demographic. It does nothing more than afford dignity to every member of society.
Political correctness prevents marginalised people from being dismissed and treated with indecency and vulgarity.  It allows us to disagree, without being disagreeable. It is a sign of a society prepared to challenge outdated language that damages the wellbeing of its citizens, thus transforming its collective culture into one of acceptance and tolerance instead of exclusion and marginalisation. 
Political correctness demonises white males and makes the white male's opinion synonymous with privilege. In doing so, it marginalises the majority. Under political correctness, if a white male talks about females, they are sexist. If they talk about ethnic minorities, they are racist. Their opinion is shot down with a litany of curse words and they fall victim to the label of Islamophobe, homophobe, xenophobe, genocide-apologist, and transphobe. Consider the case of Richard Kemp, the former commander of the UK forces in Afghanistan. Kemp was shouted down at a meeting in Sydney, Australia for simply stating a pro-Israeli political position and labelled an enabler of genocide. In this respect, political correctness doesn't promote inclusivity for everyone. It promotes inclusivity for everyone except the majority. It demonizes the white male and puts the feelings of the marginalised ahead of the feelings of the majority. It isn't even marginalised communities who are the most offended by un-PC microaggressions. It is just liberals that get offended. Those most likely to support political correctness are white people with a college education who earn more than $100,000 a year. Even the communities political correctness is supposed to protect are ambivalent or actively dislike the practice. 
[P1] Political correctness helps us use inclusive language. [P2] Inclusive language causes less offence and marginalization. [P3] Therefore, political correctness has a positive impact on society.
[Rejecting P2] It doesn't promote inclusivity, it just demonises the majority.