For bombs to be decisive, they have to be used to break the will of the populace to continue fighting.
Since Nagasaki, we have refused to do this.
For the Japanese fighting WWII, life ended after death. Death was the end. For the Muslims, however, life starts after death. Death is the beginning. They do not fear death. They will march on. Be willing to go all the way to "end" it.
Not talking tactically here, where a bomb is sometimes just the thing. But stratregically, it’s hard to see how you could stop ISIS-type recruiting on six continents and every U.S. city, college and soccer team, with bombs. There’s not a good fit between means and ends here.