To answer you in part, Nightwere, War is a necessary part of Human survival on this planet.
A contradiction, you say? Look at the capitalization, hence the emphasis. The -Human- survival, not a race's survival.
Without war we would be a plague (Even more so) upon the face of the earth. We'd eat everything, and die of starvation and when nature revolts against our destructive rule.
So, war is not good, but a necessary evil. I fight for the things I believe in, so do my opponents. They might be fighting to feed their family, or they might be fighting because they believe in what their country is doing. Does that make us both right, or both wrong when we aim down our sights?
As you also stated, peace begins to Stagnate. After a long period of peace, the peoples involved begin to grow sluggish and dull, there's something inherently natural about war to our species. Without it, we will slowly wither and die without needing to point guns at one another. And besides, my idea of peace is entirely subjective; unless you go on the book definition of 'No War=Peace' then we might be able to agree. So, even in peace human beings disagree, and war is entirely over disagreements. Peace is corrupted, and leads to the debasing of morals and values.
Note: After World War II is when the American 'Good Boy' persona started dropping. The 'Fonz' took over, and slowly began getting worse and worse. Women had a sense of decency, and duty, and self worth. Men knew where their priorities lie: Any order of the three for God, Country, Family. Maybe even two values if you're an Atheist.
Today is all about self fulfillment, and this is where people like KJI and Hu Yuan get their kicks. If they, as dictators of their own nations, do not mete out what their people desire then they have a rebellion. If America, the ultimate consumer of Fossil Fuels and with the highest assumed standard of living does not provide health care, public transit, high quality school, safety, Etc etc etc then the Americans will overthrow the Gov't. It's what we do. (Sorry, you British people reading this!

Still love you guys.)
So, each Gov't is bound by the rising majority of people who want instant gratification on everything, and are raised on the belief that they are entitled to that gratification simply by being born. It's an explosive situation, and I'm pretty sure I've rambled pretty far down the road of 'Is this really relevant'?
Suffice to say, I agree Nightwere!
I always make these replies drunk, damnit....