Because even though officials now admit the threat level is down and al Qaeda is quiet, the security for this inauguration day will be unprecedented: massive road blocks, mass surveillance and up to 10,000 security forces, or about one for every 25 visitors.
In short, by the time the inaugural parade reaches a point on Pennsylvania Avenue, the president will be in the middle of a literal fortress - a fortress pushing out from the parade route to enclose 100 square blocks of downtown Washington where all vehicles will be barred and no person can walk without a thorough search.
And it's all by invitation only. Even the inaugural tickets themselves have been designed to foil counterfeiters. And when visitors do get to their events - gridlock and weather permitting - everyone goes through magnetometers, even the marching bands, says Joe Trindel of the Federal Protective Service, which oversees most buildings along the parade route.
Asked if there will be snipers on the roof, Trindel says, "We have 'observers' with tactical capability."
Which is a tactful way of saying, of course there are snipers on every roof, not to mention chemical and bio-weapons sensors in the subways, fighter jets in the sky above and conspicuously-armed federal agents every 20 feet on the ground below. Because in this day and age the watchword is: There's no such thing as playing it too safe.