I do think intent can matter at times. Perhaps what I'm more zeroing in on is that idea that I don't find saying you didn't mean to, when you repeatedly kill civilians in very large numbers, such that certain countries have a long history of being on the receiving end of American collateral damage, as an acceptable rational/excuse. (This last part is why I think you're examples are not particularly apt)
Your intent just stops mattering as much when the body count gets to a certain number and you show no signs of changing the behavior.