And, had France or Britain attempted to enforce the treaty, would have sparked a war anyway.
WWII was a completely unavoidable event. There were other parts of the world which played into the factors, such as Japan, which was also trying to expand it's own empire, in belief it was their only way to survive.
I don't agree with that assessment, but I can respect it. Remember as manipulative as Hitler was, his hold over the German Army was extremely tentative, basically he was relying on promises he never intended to keep to have them on his side. The German Army knew they didn't have the firepower to stand against the French and would have capitulated at the first sign of resistance. Read "The Rise and Fall of the Third Reich" as it provides a very in depth explanation of how fragile Hitler's grasp on power was in the early 1930's.
Japan was a different beast altogether, remember they basically had no choice but to attack Pearl Harbor because of the American oil embargo and FDR's ultimatum for them to get out of China. Was their invasion of China a good thing? Of course not, but the inability of the Emperor to accept that he had to rely on external forces to keep his country going forced the issue from his and his ministers nationalist and racist point of view.
We will always be doomed to repeat war. War is fueled by hatred, which has existed since the beginning of mankind, and sadly, will exist till the end.
I refuse to agree with this, there is always a way out of bloodshed. It just takes people realizing how silly nationalism and racism is and that all of us on this planet are interconnected and cannot exist without the others, regardless of nationality. We don't have to like each other

we just have learn to live with each other and celebrate our similarities and to share our resources, of course. Maybe I'm being too idealistic here, but I refuse to believe that war is inevitable.

Lessons learned? Some learn how horrible war is... while other learn how to fight it better/more efficiently.
Unfortunately, we have too many different views of what is wrong, and what is right in this world. And, when two or more groups with different views meet, they clash.
I don't know, I'd like to think that WWII is a clear example on how insane racial theories coupled with unbridled nationalism are a clear recipe for destruction, but considering recent events on the African continent people haven't learned to celebrate their similarities with those that are "different."