placing himself in the role of the outsider yet again, bowie recreates the american dream and paints it in much more darker tones than expected. call it an irony, a statement regarding the destructive state of not only america, but the entire world. he is zooming in on the overlooked brutality of the ending of the 20th century, yet at the same time, presenting the inevitable havoc of the following century. again, the harshness and brutality of the instrumental accentuate the theme of the song.
My theory is that the song is about John Lennon's murder, since the his murderer was American, and Bowie keeps singing about a "Johnny". But maybe it's simply saying that America and Americans are shallow and destructive; instead of adding to the world in a meaningful way, they take the basest and the easiest path. Great song.