The fallacy of your argument is encapsulated in your statement

The Taliban and Al Qaeda are not more fearsome than even the remnants of the Wehrmacht and SS.

The feasibility of occupation has almost nothing to do with how "fearsome" an opponent is. The Taliban are miserable fighters, but they have access to an almost endless stream of recruits from Pashtun areas in Pakistan and funding from the ISI, just like the Viet Cong in Indochina. The Viet Cong were a disciplined but ineffective fighting force, and after they attempted a direct confrontation with US forces in the Tet Offensive, they were wiped out as a military force (and replaced with North Vietnamese regular forces, who continued the war in their stead).

There were several reasons why occupation worked in Germany and Japan: (1) both countries recognized that they had been defeated in a war that they knew they started, (2) the level of destruction to their cities and towns was so great that they were largely dependent on the occupying forces for even the basic necessities of life and (3) both had a culture of obedience to authority; in the case of Japan there was an added benefit in that the Japanese emperor was allowed to remain and urge his people to cooperate with the occupiers.

In places like Iraq or Afghanistan, there are tribal loyalties and blood feuds. Both profess a religion that is radically different from, and in the eyes of many (on both sides) actively hostile to, the dominant religion in the US. Both are steeped in an anti-colonial, anti-imperialist message. Both have porous borders, easy access to massive amounts of explosives and fanatical recruits (or at least people desperately poor who hope to help their families with suicide attacks).

If you are suggesting total destruction of everything in Afghanistan in order to make the people so dependent on us that they would never dream of attacking us, you're going way farther than I had suggested. I think that our reputation would suffer too much if we took hundreds of hostages, executed them in collective punishment for attacks or razed whole villages. Don't get me wrong; it would work. That sort of counterinsurgency, though, borders on genocide.

My point was just that we should, as a cost-saving measure, announce that we don't follow the "you break it, you own it" policy when it comes to other countries. It would have saved us hundreds of billions of dollars in the last decade.