Numbers. As the population increases, our form of government will continue to become less effective. The more of us there are, the harder it is to get everyone to agree - on anything. Democracies rely on some level of unity and homogenity in the beliefs a mindset of 'We the people' to maintain social control. As our population becomes 'us' and 'them' rather than 'We,' common ground and common sense disintegrate, as does our commitment to peaceful coexistence. Increasing restrictions on freedoms is an example of the government trying to control a people who have abandoned self control.
As I read that back, it occurs to me that us and them are objective pronouns, while is subjective. There's probably something significant in that.