So how many civilians would these bombings save, and how many would they kill?
Let's take a really rough and upper end number like say... The same as the entire population of Syria (19 million people). I don't know where they're based or where they currently hold but I can't imagine it being possible to exceed killing that many innocent even with an extremely aggressive campaign.
This staves off a group literally trying to send the world to Allah in an apocalypse, so the population of the planet (7.5 billion people).
Fight terror with terror, cauterize 0.25% of the population to save the rest.