If we hold up the yardstick of the long historical chronicle of civilizations, not the yardstick of utopia, we see how hard it is to sustain individual freedoms guaranteed in the Bill of Rights—and this makes us revere our nation all the more.
Presumed Guilty: The Plot of the New Civics › American Greatness
“How can we offer an account of U.S. constitutional democracy that is simultaneously honest about wrongs of the past without falling into cynicism, and appreciative of the founding of the United…

This is well worth reading in its entirety. I would add that the question almost never asked in any of this rethink of history is whether what emerged at the founding was better than what came before? Was everything peachy in the new world prior to the arrival of the European pilgrims? This question usually goes begging because the answer undermines the revisionist narrative. Various and sundry native Americans made a practice of rape, mutilation, kidnapping and cannibalism. The western Europeans who were in conflict with the native Americans certainly committed their own atrocities from time to time. But the distinction that should be made is that western European culture was heavily influenced by a Judeo-Christian worldview, the moral arc of which bent away from such atrocities. By committing atrocities, the settlers were acting against their own moral values, while the native Americans were often acting consistent with theirs.  

I'm not, of course, suggesting that all native Americans were cannibals nor that all white settlers were saints. Nor am I saying that everything done or believed by the Europeans and their descendants in North America was worthy and good. Nothing of the sort. But we ignore questions of worldview and cultural morality at our peril -- that is,  if we are sincerely interested in gaining an actual understanding.

That the complainers about the historical conduct of white European settlers are not themselves subject to an on-going risk of being raped or eaten in the present day is, at least in part, because of the long ago triumph of the moral values of the very western culture they now condemn.  

Whining, ungrateful children, they are sawing off the branch they're sitting on.