That's different, because the US destroyed those places in a legitimate war. The initial reason for war was not to help the German and Japanese people who were suffering, but to prevent Hitler from taking over Europe and beyond. Besides, the context was entirely different than it is today.
If you think that the fact that Country X is poor, undemocratic and corrupt is enough to take the place over and run it as a protectorate until they see things your way, then that would leave about 60% of the world's nations as legitimate targets for "regime change". If you set out to "help" the world, even when they obviously don't want it, the result of that, regardless of the intentions (which are almost never altrustic to begin with), is usually just as bad as if you had set out to **** them up.
Surely you must see how dangerous that logic is. Because all you need to to is say a few sentences about how it's helping the poor and oppressed, and every imperial intervention suddenly gets a bright, shiny coat of legitimacy. Take for example Iran. The arguement could be made, with sufficient spin, that they are living under an inhumane, totalitarian regime that is universally despised and would welcome their liberation from the cruel, theocratic maniacs running the place. Except that's not true. That same arguement could be made and sustained, with the help of spin and selective information, about several dozen other nations. But does that make it OK to attack them and impose what you believe to be a better way of life? Emphasis on the words "you believe".
