Frankly, does it matter what the lyrics are? Half of the lyrics are unintelligible, and the other half is somewhat ambiguous, and you really have to pay attention to get the actual meaning of the song. To anyone but someone who's sitting at home actually listening to the lyrics, the song seems like an obvious fist-pumping american anthem, and if Springsteen didn't want people to think that, he could've tried not making it sound so anthemic. If politicians use it, I don't think it has much to do with their allegedly low intelligence. It's probably rather that they don't care about the actual message of the song, they care about what the song CONVEYS. And to 90% of people, it conveys "AMERICA, FUCK YEAH!"
I think he's being sarcastic, but I think the real reason most people don't get it is that he slurs like a drunk, in addition to his somewhat oblique lyrics.