A study on working environments shows a PC culture fosters creativity and innovation.
Research indicates that working in a politically correct environment boosts creativity and innovation. A study carried out at Washington University in St. Louis involved asking groups of college students to come up with business ideas for a new restaurant to be opened on their campus. Some of the groups were given no prior tasks and told to get straight to it. Others spent some time reflecting on instances of political correctness they had recently witnessed or heard about, thus bringing political correctness to the forefront of their minds. The study concluded that in diverse groups of both men and women, those that were first exposed to PC culture came up with more restaurant ideas. The ideas that they came up with were also more novel. 
The study proved that when exposed to a culture of political correctness, people feel more able to speak their minds and feel more at ease. Political correctness sets clear boundaries on what speech is acceptable and what is not. When these boundaries are clear, everyone can express themselves with confidence without fear of being hurt or offended, or of hurting or offending anybody else. Ultimately, this makes for a more creative and innovative society.
This is just one study. The author admits herself that there has been a dearth of studies examining the effects of political correctness on group behaviour. Also, this study only examines political correctness in the workplace. That is only one aspect of political correctness. Most critics of political correctness do not argue that PC culture is detrimental to the workplace, they argue that is detrimental to free speech and the marketplace of ideas. This study does not disprove that PC culture has a negative impact on freedom of speech in the public sphere, only that in the very specific context of a meeting in a professional environment it MAY contribute to creativity and innovation.
[P1] Political correctness allows us to be more creative and innovative. [P2] Therefore, it is of benefit to society.
[Rejecting P1] There is not enough evidence to say this with certainty.