The choice of tactics can and does influence the behavior of the people one is fighting against, or people who may be contemplating violence. If it didn't why would our military have made so much effort to avoid behavior which would upset the people in Iraq and Afghanistan?
Because we are being led by people (especially the Obama Admin.) who have no idea how to win wars.
I'm not saying that civilians should be deliberately abused in wars, and, if they can be co-opted, great. But, we hardly avoided "upsetting Germans or Japanese" in WW2. We SMASHED them, such that very few had any fight left in them once we occupied those countries. Then, we treated the survivors humanely.