It’s been thirteen years. I was five years old and watched towers falling, people jumping to their deaths, and the Pentagon burning. I saw humanity at its worst, and like most posters in my age group, it is burned into our memory. In fact, it is my earliest vivid political memory.
That being said, it has been thirteen years. I am over it. I will briefly pause to think about it, but as time goes on, so does life. So no, I will not be removing my avatar and I encourage everyone to do the same. Getting teary eyed over an event so long ago is exactly what Osama Bin Laden would want us to do.
I'll continue to commemorate American tragedies of this scale each year for the rest of my life. It shaped my generation and global politics since. It has absolutely moved from being a day of renewing wounds to a day of commemoration, and there's nothing wrong with that. We still rightly commemorate the attacks on Pearl Harbor, which was almost 3/4 century ago.
And just because you will abstain from changing your avatar doesn't mean you need to encourage others not to change their's. That's not in very good taste IMO.