We no longer live in a civil society, at least not in one where civility is important. Think about how easily people resort to serious insults and slams quickly when they are bothered in the slightest.
Our current political contest is a good example. People on all sides almost demonize those they oppose. While the charges made may have an element of truth, doing such continually leads to a situation where it takes more and more to shock people into action. Where a mild charge would once have been sufficient to provoke extreme outrage, outrageous charges are now necessary to provoke any response at all. Even then, people are so numb to such things that they frequently just mentally "change the channel" in their brains when they hear such.
It is like a drug user: Each time, more and more is required to reach the same high, until the user finally reaches a point where a high is impossible, but a high level of consumption of the drug is necessary to just survive and avoid extremely painful withdrawal symptoms.
While I see this as a problem across the political landscape, I see it especially clearly in those who are socially liberal. They steer from reasoned argument and make villains out of those who disagree.
What is the answer? I don't see one, short of a Godly revival sweeping the land. Without God's intervention, we are headed for a crash. Though some people I greatly respect see that coming, I am not convinced. I have a sense we are headed for some mighty rough times, ones that will require a full reliance on God to survive. However, I do not believe these will be the "end of all time," as many speak of, but rather I see a rough period of reaping for all the horrible sowing modern man has been doing. History has examples of this. Life goes on, but it can be more difficult at times.
How does this relate to incivility? I believe you cannot establish a stable society without some ability to coexist without letting everything be very personal. Without that, even minor battles become major skirmishes, and they will end up with only one winner and one bastion loser. Even the winner in this case doesn't get what was expected, since the cost will have been paid in human lives.