Contra Brian, while I do think the system is calcified and rigid in unproductive ways, and plundering is the order of the day among elites, this is not exactly an unprecedented state of affairs in US politics. There have been several periods (some of them even have names, like 'The Gilded Age', and 'The Age of Robber Barons') where the brazen use of power at all levels has been corruptive and corrupted.
This too shall pass.
On the other hand, I think the great and unique legacy of the US from a social-political point of view is that we are ever seeking to expand and include what were previously "others" into what we mean by the word American. Granting rights to social groups equivalent to the dominant group after a hardfought battle is a social heritage of the US. It’s “what we do” as a culture, I would say at this point almost compulsively. It's much like what Nietzsche said about freedom; it's the fighting for freedom that makes one free, the structures that come afterward in victory are almost appendices.
It's a one-way social ratchet of awesome. It is this more than anything else that allows me to say (not ironically) that I'm proud to be an American. And so while our tendency to set other people's countries on fire from the air without thinking all that much about it is extremely worrisome, it's not the be-all-and-end-all of what the US is or what we are.