You are making excellent points. There is no justification under any circumstances to "justify a campaign of aggressive expansionism predicated on ethnic cleansing and settler-colonialism." I fully agree with that.
You are absolutely correct on Germany and Japan. However, we should not underestimate the Bretton Woods, which created a dollar-based global financial system anchored in the American economy, and the U.S. Navy’s global dominance after WWII which created stability and growth for export-oriented economies like Japan and West Germany and later on South Korea, Singapore, Hong Kong, and eventually China.
Before 1945, the Great Powers (Navies) of the world had competed with each other for control over critical chokepoints for centuries since the era of deep water navigation. But after WWII, free trade became possible because of U.S. naval dominance, which replaced centuries of gunboat diplomacy. This period has been historically unique.
IMHO, it was made possible not only by the collapse of the British Naval dominance but also by the fact that the Soviet Union emerged as a continental, land-based superpower, leaving the oceans to the United States.