to the point, if Al Qaeda would have taken out DC instead of NY, I'd have personally sent them a thank you card. Irrational? Perhaps to a segment of the population, but another segment would have the exact same feelings.
Just the same when Bin Laden was killed. You had almost as many people saying what do you get with him dead? Nothing's changed, but it's a cathartic experience for those who gain something from it, much like slapping Kevin Dunn would be.
I use the two above examples solely because they were when I started looking into ethics and rationality.