That's true. Many countries romanticize their histories. And I totally agree with your second point.I don't know about this. A lot of countries romanticize their worst defeats. Britain has Dunkirk and Australia and NZ have Gallipoli.
I do think, however, that American Government and media exploit their defeats to inappropriate ends. They use the fear generated by shock defeats and possible future attacks (no matter how unlikely) to whip up a fevour for bloody revenge. Would the American public have been so passionate about (illogically) going to war with Iraq if it hadn't been sold to them as a way to right what happened in 9/11? 9/11 is being used over and over again to serve whatever cause that is chosen. I find it extremely disrespectful for the dead to be practically dug up and paraded around the room to manipulate the public.