I agree with what most people here have said. Superman was created in America, and was raised in America. He doesn't need to abandon his identity to save other, or to serve others. The very nature of Superman is that he stands for what America is supposed to stand for. People need to understand what things really mean. If Superman says he fights for "The American Way" it doesn't mean he fights for Oil or the furtherment of the USA, it means he fights for what "The American Way" is supposed to be, meaning life, liberty and the pursuit of happiness, equal treatment for all citizens, so on, so forth....
I can understand anti-American sentiment, even as big a patriot as I am. But people don't need to be hurt by a character being so clearly an American icon, you'd have to be supremely narrow minded to be hurt by that. Things aren't so black and white; because he's an American icon and he fights for "The American Way" doesn't mean he's more loyal to the US than anybody, and it doesn't mean he will ignore others for America, and that doesn't mean if America does something wrong that he'll stand behind it. He fights for the American Way, even if America itself has lost sight of what that really is.