War in itself isn't a bad thing. It is the acts committed during war that might be bad. People didn't exactly die in the Cold War, and at the end the U.S.S.R crumbled.
War IS needed because you can't solve everything diplomatically like the Europeans want to do. Diplomacy didn't win World War I and II. Diplomacy didn't get South Korea their freedom. Diplomacy didn't settle the issues in Bosnia. Diplomacy didn't settle issues in the Middle East. Sometimes, bad as it may sound, war is the only solution.