The way I see it, there's a certain hierarchy to the response to a tragedy, at least here in the US. The severity of the catastrophe is part of it, as is where in the world it happened, and whether it was of human doing or an "act of god", as it were. 9/11 resulted in a fairly severe loss of life, happened within our borders, and was an act of aggression against civilians. As a combination of being on the higher end of several spectra, it had a profound effect on American mentalities.
Through the years, I have seen strong responses to tragedies that have occurred all over the world through American eyes, and they have been similar, though not necessarily held onto to the same extent. Japan, Indonesia, Haiti...Americans have felt emotional responses to many tragedies since then, but tragedies in your own country are always going to be seen in a different light. Even Katrina, though effecting many Americans in horrible ways, was an act of nature. And if acts of nature are scary, acts of man are terrifying.
To be frank, 9/11 scared the shit out of Americans. There was no way of knowing if there was going to be another attack. People felt unsafe in their own homes. In a lot of ways, it shook us. It wasn't like Oklahoma city where it was just one guy...it was a network of people that were willing to go to extreme measure to make sure civilians dies. It was a network we knew fuck all about and I feel like even now we don't know that much more.
This is all just coming from the eyes of someone who was 8 when it happened. I strongly believe that the events of that single day shaped the events of the majority of my life in ways I can't even imagine. For a lot of Americans, it was like the first time one of your family members dies, or the first time you lose a pet; the first time your house is burglarized or the first time you're mugged or the first time you realize your parents aren't invincible. It's that day that changes how you look at the world, that makes you question your safety and the way you look at the world. It was a profoundly changing day.
But for a lot of people it was also like the first time you witness someone do something nice to a stranger for no reason, or seeing someone stand up to a bully for someone they don't even particularly like. It was a day that made you see that there were good people out there too. And I think, more than anything, it was that twisted, perverse blend of tragedy and heroism that made it stick so strongly into our minds. It was a day that made a lot of people stop and think, even if they didn't know a single person who lost their life. I'm not saying by any means it was the worst thing that's happened ever, but for a lot of people it was kind of a perfect storm. I guess that's why I don't really begrudge people their reactions to it even now. That being said, there's a special circle in hell for anyone who has ever used it to further their own interests.
Wow, I'm way into TL;DR territory and I doubt a single person will read this but it was good to think this all out and write it down anyway. Very therapeutic and all that.