When a high ranking member of any enemy organization, be it military or terrorist, dies, it should not be celebratory news. Celebration should be saved until the enemy has surrendered and troubles you no more. The Soviet Union survived the deaths of Lenin and Stalin. The People's Republic of China survived the death of Mao. The Macedonian Kingdom survived the death of Phillip II. Rome survived the death of Julius Caesar. Carthage survived the death of Hamilcar. The British Empire survived the death of Nelson. When Osama Bin Laden died, Al Qaeda continued on.
Sometimes, as in the case of the Macedonian Empire, the structure does not survive without the one who built it. Often however, all that has been done is to clear the way for another to take over. This other might be more or less capable than their predecessor (compare Phillip II to Alexander the Great), but you cannot count on the threat to end with the leader.
So don't tell me when Al Qaeda leaders are killed. I just want to know when they're no longer a threat. That is when I'll celebrate.