Well, it certainly isn't that European peoples themselves are somehow fundamentally different human beings. That theory has been put paid so many times I don't really even want to dignify it with addressing it - rather, that humans and the cultures they form are products of interplay with their environments. Europe, historically and probably to this day has some specific characteristics that should be recognizable. Let's take one of your more horrific examples in that long and good post of yours - Imperial Japan in the 20th century. Not only was it a country rapidly arming to "catch up" with rival powers in order to exert its share of power on the world stage it had some fundamental characteristics that should be warning signs. An industrializing/industrialized power when compared to its neighbors, heavily populated to just flat overpopulated, and an economy that more than anything needed space and resources to continue on its path of prosperity since it was relatively manpower and skills rich and relatively resources poor.
Not that this is necessarily a recipe that spits out Imperial Japanese aggression, but rather a situation in which an increased likelihood of bad friction is present. Imagine a USA that couldn't Drill Baby Drill when it feels the pinch.
I'd also agree with Hobbs that some of the rumbling for Europe to start arming does stem from what are not entirely unfounded fears of the rising Middle Kingdom.
Sorry for my late reply--I'm terrible about getting back quickly--but thanks for this reply.
Tim definitely seemed to be suggesting that Europeans are uniquely and inherently violent, and need to be controlled by the US and Russia, which he thinks are more responsible with power for some...reason.
But anyway--Imperial Japan was a perfect storm of a rapidly industrializing and growing country with political unity, a strong military, weaker and less unified neighbors, a desire to emulate and match other imperial states, and the worst case of ultranationalism the world has ever seen, to the point that when the Russo-Japanese War ended, there were riots in Tokyo because Japan did not annex as much land as people expected it would. Circumstances made up a lot of the ingredients in the mix needed for Imperial Japan to bring hell to earth, but if it hadn't been for that unbelievable amount of nationalism and warmongering, it's unlikely the military leadership would have been anywhere near as bold or insubordinate as it was.
Modern Europe has few, if any, of these characteristics. There's a largely strongly pacifistic youth culture and pacifistic older generations as well. The population definitely isn't growing quickly in most European countries, and declaring war on a neighboring state and annexing its territory became almost unthinkable there after the war (Yes, Putin seized his own Sudetenland, but I'm not counting Russia as "Europe" here, because it tends to be in its own distinct sphere and this thread is clearly talking about NATO and/or the EU). Only a handful of political groups in Europe, chiefly Jobbik, even dream of anything like that. Fortunately, Hungary is powerless to try Crimea-style takeovers of Slovakia, Transylvania, and other examples of
terra irredenta even if Jobbik gained power. Most countries in Europe are much more closely intertwined than they were in 1939 or 1914, and the better part of the public in most EU countries are hesitant about air strikes on terrorist groups in the Third World, let alone full-scale wars of conquest against their own neighbors. Most of Europe has moved beyond that long ago. Russia hasn't, and still thinks like it's 1914 when it comes to laying claim to whole ethnic groups and their lands (handing out passports to Ukrainian citizens of Russian background and then claiming the right to "protect" them, claiming to represent Estonians of Russian background, etc.).
I think that the overall
Zeitgeist of Europe is pretty pacifistic; if informed that the US would withdraw most troops and force Europe to spend more on the military or have less protection, most European states would either not re-arm or do so only partially and grudgingly, preferring a softer stance towards Russia over an expensive and politically unpopular rearmament program. Which, of course, would only embolden Putin--we've seen this before.
Every nation needs a military to protect itself. Not to mention, the US, Russia, and (to a lesser extent) China have military obligations to their allies which necessitates the maintaining of a large and capable military to fulfill. 
