As usual, Lileks says it far better than I ever can:
I have less to say on the fourth anniversary, because I’m not sure what needs to be said. You get it or you don’t, and if the passage of time has made the lessons indistinct, a picture of that September morning will look as remote as a screen grab from “Tora Tora Tora.” As Mark Steyn put it, we are winning the war on terrorism, but perhaps we are losing the war about the war. I’ve seen this happen for a year and a half – hell, since the first reports of Quagmire and the Brutal Afghan Winter. Between the incessant pessimism, the lack of focus, the interminable litany of sins from Abu Ghraib to Gitmo, the tepid wind-chimey spirit of the memorial culture that would rather put a vague sorrowful half-circle in a Pennsylvania field than a monument to courage and half-crazy bravery – well, the floorboards where our betters live are rotten with doubt, and they hear fatal creaks every time they dare take a step. So there’s not much point in wondering where this will go, because it’s already there – and the next time IT happens, we will not wait a month or two before the doubts and attacks begin. A London or Madrid-style attack will expose our divisions more than our solidarities, at least in the media. Anything worse will make such chatterings irrelevant, and as attractive as that sounds, you really don’t want that.
[…]
I wish they’d build it again. The same two towers. Because we can. Because they can’t.