Why is it that the Modern Warfare 2 "No Russian" scene went too far?

[twesterm]

iLLmaticV3 said:

Maybe because of 9/11, people don't like the idea of terrorism, and stuff like that. It bothers them.

This scene may remind people of that and bother them, I personally don't care.

Why is anything 9/11 taboo?  Is it because it's in our lifetime?  Is that why it's alright to make jokes all day about Hiroshima? 

Is their tragedy somehow less because I didn't wake up one morning and see that on TV?