But it is mine. Superman's foundation has been set for a very long time.
I understand it was something the Fleischer cartoons started to prop sprites when the gloom of war was hitting American shores. And I don't disagree it was a vital part of the character for a long time.
However, if you've picked up a comic anytime in the past twenty years, you would realize that Superman isn't so undeveloped as he was. Since the end of the Cold War, writers have taken the opportunity to explore different aspects of Superman and explore the fact that he is an alien, and one who doesn't always agree with the way that humans act. As previously mentioned, there was even a story where Big Blue abdicated his citizenship which caused quite a controversy but did enable some new insights from a character that is over seventy years old.
The simple fact is, Superman has by and large been portrayed as a defender of America, but in actuality he is a defender of all mankind. We've had plenty of examples of his pride in his home country over the years, but quite honestly I hope that's all left out of the new film. A scene where maybe he straightens the flag would be nice, but something as blatant as the end of Superman 2 would seem insincere in this day and age. That kind of display is out of touch with the way the world is now, and not concurrent with the character at this point.
During WW2, the phrase "truth, justice, and the American way" was created as a rallying cry to unite Americans. With the current landscape of the world, a world which is smaller than its ever been, Superman can be used to unite all mankind and portray how great humans of all nationalities can be, not just as some sort of inclusive cheer which it has become over the years. If the filmmakers attempt to tackle such a subject I would be incredibly pleased and it honestly seems like the next logical step for the character to take on the big screen.