re: The Blitzkreig didn't destroy the Brits will to resist.
Had things gone slightly differently, and allies had not entered the war on Britain's side, damn straight their will to resist would have been destroyed. WWII could have gone a lot differently.
The "defense" theory falls down in this current conflict because war isn't simply about keeping an army away from your borders any more.
The goals of this war, and the war in Afghanistan, have been spelled out specifically. Many times. The reason regime change and reconstruction are needed, not just destruction, have been explained. That you choose to ignore it is your problem. You and others have stopped listening to anyone except yourselves a long time ago.