How is "War is hell" always used an excuse for everything? It only makes sense if the alternative is a worse hell. Otherwise it seems like a great reason not to do something like this.

People seem to act as if it means that you can call something "war" and suspend all ethics. Maybe if I feel like punching someone in the face, I could say "Hey man, getting punched in the face is hell. What are you gonna do?"

Maybe that's the blasé part of it that you were referring to.