I'm only a year older than you. I thought the point was that now on domestic soil, they're able to do stuff like this and that we are no longer safe and "stuff that happens overseas and far away" could potentially happen here.
And then, it wasn't much longer after that, maybe a year, that I realized that the big deal was that we keep pushing people around globally and pissing people off and making enemies and, "innocent" individuals aside, we, as the USA, probably deserved it.