If future societies are condemning our behavior now, then we would not have progressed that far.
This isn't about kindness and cruelty, this is about awareness. As long as we perceive other living beings as The Other, we're not truly aware -- we can't empathize, we can't be compassionate, we can't be a complete human being. Condemning people for barbarism is a subtler form of separation, of saying "those people are not us." But they are, just as we're growing as a species and society to be aware of non-human awareness.
This isn't about kindness and cruelty, this is about awareness. As long as we perceive other living beings as The Other, we're not truly aware -- we can't empathize, we can't be compassionate, we can't be a complete human being. Condemning people for barbarism is a subtler form of separation, of saying "those people are not us." But they are, just as we're growing as a species and society to be aware of non-human awareness.