Yes, indeed. That explains, but doesn't justify, the use of bombers in area attacks directed at civilians. Such justification, if it is available, must be found elsewhere.
I would not accept from IS, even if it was fighting a just war (which it is not) the argument that "we must encourage random murders of innocent people by deranged fanatics because it's the only means we have of striking back at the West" as a justification of their encouragement of these crimes.
One reassuring thing so far. Only complete madmen have so far answered the IS call. They don't seem to have any organised cells capable of effective coordinated action. I hope that remains the case.
