Wars are contrivances, used as tools to manipulate societies.

I do not see the pretexts for WWII as having differed from those of any other wars the world has known.

Yes, in general war is used to manipulate societies, but that's not all that's involved every time - and wasn't in the case of WWII, particularly on the Allied side. Hitler did use war to help drag Germany out of its economic problems and to exert control over society  by restoring national pride (after the humiliation of defeat in WWI). However the British establishment in general and most of the public did want to avoid a rerun of WWI  which had caused such huge losses - hence appeasement.  Churchill was a relatively lonely voice warning about Hitler and German rearmament. Hitler forced the issue by invading Poland (rather different from Vietnam - which was invaded by the US). The American population in general were not interested in getting involved in another European war - and Hitler actually declared war on the US, while, as I said, the Japanese did attack Pearl Harbour.

SO there are significant differences between WWII - on the Allied side - and later imperialist attacks by the US on Vietnam, Iraq, etc. This is reflected in the differences in attitude of most Allied WWII vets and vets of later US attacks. The difference is significant, not hair-splitting.  

Similarly I think it's over-simplifying to say that

we... accept indulgence in these same infractions time and again. Repeatedly. And, moreover, relentlessly, today?

If this is not sign of deep-seated illness, what measure should we be using?

Again there are differences in the public's response to various wars which are important and which don't mean we're just doomed to go on making the same mistakes. As I've pointed out before in ET, Chomsky is pretty cynical about the powers that be, but not pessimistic about people in general:

Looking more closely at the anti-war movements in both cases, I think, as noted, that it has actually been greater in the case of Iraq than it was during any comparable state of the Indochina wars. Furthermore, this country has significantly changed as a result of 60s activism and its aftermath. The movement against the war in Vietnam, when it finally developed, was not "diluted" by the wide-ranging concerns of activists today. I can easily elaborate even keeping to my own experience. Consider just talks. In the late 1960s almost all requests were about the Vietnam war. Today, only a fraction are about the Iraq war, not because the war is not a concern, but because there are so many other live and important concerns.

Furthermore the deluge of invitations is far greater in scale, on all sorts of issues that were scarcely discussed 40 years ago, and audiences are far larger and much more engaged. And there are many other factors detracting from activism, such as the enormous amount of energy drained away by the "9/11 Truth Movement." There may be an impression of less anti-war activism today than in Vietnam, but I think it is quite misleading - even though protest against the war in Iraq is far less than the crimes merit.

http://www.zmag.org/content/showarticle.cfm?ItemID=11718

And the disillusionment of the US military has set in far more quickly in the case of Iraq than Vietnam.

Maybe it's because I'm a Londoner - that I moved to Nice.