Why is it necessary? This author was on the right track talking about the symbolism, but it goes a bit further. Have you ever asked yourself why the Japanese and Germans don't still hate us en masse? We didn't end WW2 just by destroying the capabilities of our enemies to fight. We destroyed their desire to fight by discrediting their beliefs. The Germans had a personality cult built around Hitler. The Japanese went even further, worshipping their emperor as a god. America showed them their gods were impotent, precipitating serious personal crises of faith among their populations.
When extremists believe in a violent Allah and worship an intangible, it's a bit harder to discredit their beliefs. Nuking Kabul and Baghdad, for example, would probably just make their belief more fervent. However the Muslim holy sites are critical to their beliefs. How could Allah allow Mecca to be obliterated? As we did with Hiroshima and Nagasaki, we would be answering terror with an even greater horror. I feel sorry for the peaceful Muslims whose faith would also be challenged, but if we want to win, that is what it will take.
I believe that when all cultures are connected via the internet and whatever else the future brings, that this will be the time when many of these archaic and ignorant cultural behaviors will be eradicated.
In the meantime, we will witness decades more of these clashes between cultures that are indeed centuries apart in civilized behavior. The babies born today in the Muslim world will still be throwing rocks in about 8-10 years....and so on, and so on, and so on,.........