We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
Every psychiatrist has had this experience with a patient, if not with themselves: someone feels down and despondent for a week and doesn't know what they might be reacting to until reminded, or until they remember, that it's the anniversary of a death, a loss, or anything emotionally painful or damaging.
We call these "anniversary reactions." (Sometimes I joke that the true "anniversary reaction" is how a wife responds when hubbie forgets their wedding anniversary.)
The human mind has a lousy sense of time (or we wouldn't be checking our sundials and calendars all day long,) and the human unconscious has none-to-little. The past always is part of the present, and vice versa. Time, psychologically, is a sort-of higher-level cortical illusion...or something.
My smartest supervisor in analytic school would say, of patients in psychoanalysis (as opposed to psychotherapy), "When they talk about the past, they are talking about the present. When they talk about the present, they are talking about the past. And they are always talking about the transference."
Thus the usefulness of anniversaries is to highlight, and bring into the sunlight, things that have been lurking beneath our attention - whether fine things or awful things.
In the case of 9-11, we hardly need a reminder, since the war of fundamentalist, militant Islam against the infidel continues across the globe, with daily reminders in the news. Still, it is a good idea to mark it because so many of us experienced 9-11 as personal, and as an unwelcome reminder, to us self-involved, semi-decadent, material-worshipping, and complacent Americans, of the existence of evil in the world, on a large scale.
It is a good refresher course in Evil: people who do not know you, and to whom you have done nothing, desperately want to kill you, even if they die in the process. It isn't sick - it's plain old ordinary evil which destroys innocence, crushes good intentions and good cheer, and pursues the death of innocent strangers in the name of a prophet and a god.
So, like Pearl Harbor Day for another generation, we will all remember our 9-11s today, whether we want to or not. It's a scar that will never, and should never, fully heal. With some things, this "healing" thing is over-rated, and only means pushing things into a past which, for the human mind, does not really exist.
It is psycho-utopianism to imagine that pains entirely go away. Humans do not work that way, and it is for the best that we do not, or we could not really learn, or grow with experience. Often, the tough lessons of life have to hurt, and life is not all about "happiness," except for the most superficial and foolish. There are deeper wells...
Our pains and sorrows and angers and memories are a big part of what and who we are: in this case, the horror of what man is capable of doing to his human brothers and sisters. Since Eden, every generation, and every person, loses their innocence.