One of those factors -- perhaps the largest factor -- is the fact that Americans love Nolan's reinvigorated Batman. We love the idea of a leader willing to take risks, a leader willing to make unpopular choices. We want a leader who will make the hard choices.
We do not elect our leaders on the basis of their continuing popularity; being president is not an exercise in self-congratulation. Winston Churchill was unceremoniously tossed from office after World War II. Harry Truman almost lost the presidency to Thomas Dewey. Abraham Lincoln came within weeks of losing the White House to George McClellan. Great leaders do not please all the people all of the time.
Great leaders are great leaders because they stand tall when times get tough. We elect leaders because we know, based on their past action rather than empty slogans, that they will stand for our ideals when the hurricanes begin blowing. That is why we love Nolan's Batman, and that is why we love great leaders. And that is why I hope "The Dark Knight" continues to garner millions of viewers.