Personally, I think half the problem is that America lately has had more wars based on abstract concepts rather than physical foes.
Take for example, the war against communism. Then there's the whole "war on drugs". Now there's a war on Terror. The only way to win such wars is to wipe out everyone that holds a specific view. That includes people in your own country with those views. Likewise, wiping out people with those specific views also martyrs those that are killed.
War on Cummunism. Gives people the message that to survive, you'd have to either go Capitalistic, or brand together to form a community to counteract Capitalism.
War on Drugs. Makes people aware of drugs, more constantly, and since we can sometimes tel when we're seeing propoganda (like with Pot), it spikes our interest.
War on Terror. Makes people realise that it's either joining people going into other countries and bringing democracy through gunpoint, or having your own ideals and spreading that at gunpoint.
Personally, I feel that an era of peace is needed, but as long as Western Governments can control societies with fear, that won't happen.