The reason is simply that people were killed, Americans, on American soil; the amount and speed at which it happened is relevent for mainly historical purposes. People didn't have to be killed, the main reason that America 'cried' so much is that it occured on American land. If someone flew a few 767s into a few American buildings(on American land) that happened to be empty at the time, America would have taken the similar measures, and would have 'cried' just as much. Speed had practically nothing to o with America's reaction to the September 11 attacks.

Thanks for letting me partake in this discussion.