I have always thought, and will always think, it was overhyped. A hundred thousand evils have happened in the world, even in recent times, that far outmatch this. It is merely given inordinate focus. Four thousand dead? The families have a reason to grieve, to be sure, but what is it to everyone else? If that sort of event is enough to shake a nation as large as the United States, then they are truly weak. Four thousand is not a huge number of casualties. Most battlefields have a worse showing, even in ancient times. How many died at Canae? 60 to 80 thousand, about 80% of those being Roman troops? Yet what did the Romans do? They didn't get disheartened. They kept fighting. The US has, as always, shown itself to be a strong nation with a weak heart.
People say 'let us never forget', and, well, maybe it's because I'm Canadian, but it doesn't give me cause for grieving in the least. We live in a harsh world, we suffer what we must. And four thousand lives ended is less than died on the average day during the second world war. What makes this so great? Because the supposed superpowers of the world were, for a day, beaten? Do we weep because of that, or do we continue onward? People must move on, and not dwell in the past. Those who were directly affected, let them grieve (but even for them, grief must have its due range and compass, and not last inordinate length.) But for me, I have yet to be shown why it was such a dire catastrophe. It is a war, and things like that happen in a war. The Israelis and the Palestinians have to put up with that all the time.
I'm just being a realist here. I disdain inordinate grieving, and value a more stoic approach to life. People who put no term to grieving have no future.
As a side-note, the event was not a tragedy. It was an event of strong emotion, of loss and disaster. But tragedy requires a certain depth of spirit capable of suffering. It is, in fact, a glorious thing, because it shows the strength of the human spirit when confronted by hardship. All I've seen from the US since then is the very opposite.