First of all, I'm not "waiting" for it. It's the very last thing I want to happen, in fact. .....Nor have I suggested otherwise. Secondly, there were plenty of "innocents" who died when we annihilated civilian targets in WW2 -- Dresden, Hamburg, Toyko, and of course Hiroshima and Nagasaki. Plenty of innocents. But we did what we had to do to win the war, and our actions were completely justified.
Similarly, taking out Mecca and Medina with nukes (if we ourselves were nuked by radical Islamic terrorists) would indeed involve killing lots of innocents, but it would be a necessary step to take to win the WOT. A lesser response would be viewed as "western weakness" and an open invitation to disaster -- more terrorism, of course. The only thing these people are capable of understanding is overwhelming strength, in case it's passed your notice.