Only because people like you seem to think it's such a big deal. If people were to look at it as it is and comprehend the scope of the matter, it wouldn't damage the social fabric.
No it's not - people die from unexpected accidents completely unaware of the risks all the time - intuitive risk perception doesn't work really well - caveman instincts and all that - risk perception is not the problem - if this was indeed an isolated incident that would not repeat it would be sad but not very relevant - an example of this is Breivik murders.
But obviously this is not comparable - people behind this will try to repeat it if not dealt with - this is why it's a big deal.
Unfortunatley from a mathematical standpoint you are incorrect, from an irrational human standpoint you have a point however.
The human mind is much worse at reasoning and reality than anticipated, how you and others perceive the world is not as real as you'd like to think, thats the whole point of math and science:
Intention is all that matters, and why its attempting to damage social fabric.
I'm not trying to be flip. I'm saying that by any viable moral theory, you are catastrophically wrong.
I'm not changing a damn thing in how I live my life, and not even out of courage (i.e. the "we can't let the terrorists win" bromide that took over in America in late 2001). It just shouldn't matter that much to you, and it only prevails insomuch as you let these irrational fears get to you.