Because this is the tenth anniversary of one of the most tragic, shocking single days in American history. And you should be able to feel whatever you want today, without someone else telling you you're wrong,and that their way of observing is superior to yours.
Those two hours between 8:30am and 10:30 were shattering to anyone who witnessed it, watched it on TV, listened to it on the radio, followed it on the Internet, or followed it third hand. We were all impacted by it. If some people feel the need to move on and not commemorate this day, fine. But don't be surprised or disappointed if many others do feel the need to grieve, pause, and reflect. Ten years is a long time in some respects, but in many other respects, it's a speck of time. The wound, to many, is still raw.
The wars in Afghanistan and Iraq happened because of the events of Sept. 11. But they didn't happen on September 11, and they certainly had nothing to do with the victims, so how you feel about the ensuring ten years shouldn't reflect on the mass-murder that happened a decade ago today.
I'm going to mourn the loss of life in New York, Pennsylvania and Virginia today, and already watched a very moving ceremony this morning, commemorating an awful day that will always seared on all of our memories. But you don't have to. You can do whatever you want today. But nobody here can or will make me, or anyone else, feel guilty for observing 9/11/01.