I agree completely that our desire in WWII was to win. As a historian, no doubt you are aware that WWII had its share of politics--not only from the left, but within the military itself. Patton believed he could have ended the war early on several occaisions, but Eisenhower was committed to his "wide front" strategy. Point being there are always plenty of views on how to achieve the final objective. Your post brings a salient point, that our War on Terror should look more like WWII than Vietnam. I agree completely. I would argue that if Truman had the weaponry available we do today, he may have prosecuted the war in Japan differently. His objective wasn't to kill as many people as possible, it was to force Japan to stand down.
I thank Truman for being brave enough to drop the first nukes. But we shouldn't be so enamored of the violence certain tactics make available. Our purpose is to defeat terror, not to create a big body count. To destroy terror, we must destroy the regimes that create it. Again I say cut as wide a swath as necessary, but no more. Vengeange on the enemy, yes. Vengeance on people who may not be our enemy does us no good.
Terror is a verb, it can not be defeated. Try radical Islam (Islam) it can be defeated.