Experienced players dominate the politics of established alliances, and it is usually these same players that have been building the most time into their nation development. They are the same ones who are most opposed to war, as they are the most apprehensive of loosing their preciously-gained pixels in a war against an opponent of similar strength. At this point in the game, where the NS of many nations is the result of years of buying infra and collecting taxes, war is unlikely.
Also, I have made this point before, but what the heck: war, from a purely game-mechanics viewpoint, is highly unprofitable and undesirable unless the war in question is an absolute tankroll over the opponent. When the opposing sides are of similar strength, it is in the interests of no one to go to war, as each side will undergo too many losses regardless of who wins.
Sure, one might say, both sides loose a lot of NS but fighting and winning the war will still yield a relative gain. That might be true, but that fails to bring about war for 1) the reasons outlined in the first paragraph and 2) the potential belligerent sides realize that in the case of war, whatever major party that -isn't- involved in the war will come out greatly advantaged.
In order words, the amount of time that this game has passed without a reset and game mechanics jointly discourage war.