Although ISIS is a big threat to all Western civilisation security, we cannot advocate carpet-bombing because it kills so many civilians in the process that we are going to be seen as an evil empire trying to spread war when we only want to eliminate specific threats in the crazy ISIS members.
People in Syria and other areas are already victimized by ISIS. They are suffering terribly, and carpet bombing and killing them would make us just as bad as ISIS. Actually, it's probably exactly what ISIS wants. They don't mind dying for their cause, and they would love to take others (innocent people) with them.
I don't think it would be an effective tactic to carpet-bomb ISIS, as ISIS has a lot of its bases in towns and cities saturated with everyday civilians. It would be irrational to demolish an entire city, just to get rid of a few bad people. Furthermore, carpet-bombing ISIS can emulate the wrong impression and motive. It would promote the stereotype that the West is against the entire Muslim Diaspora, rather than just being at war with the extremists.
In the war against ISIS, carpet bombing is acceptable in trying to defeat them. Many people may find this inhumane, but the way that ISIS members inhumanely slaughters innocent people is worse. They decapitate Christians and non-Muslims for simply not being Muslim. They have declared war on America and must be dealt with appropriately. However, the only time carpet-bombing should not be allowed is when there are innocent civilians in the area. We should not stoop down to their level and kill the innocent.