We get a lot of raw materials from Germany, South Korea and Japan? Mainly, we are abroad because the post-WW II generation loved feeling important and rubbing the europeans' noses in the fact we were on top. Plus, having a far-flung empire justifies a lot of State Department and Defense Department jobs. Do the Chinese feel the need to have bases all over the place? The Russians?
I did say "largely" for this reason. For a time our FP was "containment" (another benefit to those seeking low cost raw materials, uncoincidentally). Those countries you list cooperated both with that intent, and also for reasons provided by WWII. If the Chinese, or Russians, could have afforded, and had had their houses in order, they'd have "taken over" the world, too. You might be very right about the jobs aspect. Every society needs to solve the problem of what to do with its young men.
I'm willing to concede that we made all these decisions for the noblest of reasons. The question we now face however is whether we need a new approach. We can't secure our southern border, yet we have 200,000 troops in Iraq and afghanistan. We can finance our government only by essentially forcing china and japan to buy huge amounts of our debt as the price of access to our markets, yet we are trying to carry on three wars at once, prop up the economy and convert to a socialist health care system. I think our priorities are skewed badly and our reach far exceeds our grasp.
So what do we fill --all those holes-- with after the military has been liquidated, or seriously at least downsized? Possibly a fulll court press effort towards the developement of alternative energy sources! Excellent idea.