I don't understand the application. Is it your stance that murderers are incapable of any appreciation for other humans? What about those who have killed others "justly", e.g. soldiers or executioners?
(I am a meat-eater, just pointing out something I find funny in such statements)
I believe we may each be using the word "appreciate" with subtly different definitions. I believe it's possible to appreciate aspects of a thing without necessarily collapsing them all into some sort of comparison of perceived total value. I think it's possible that someone who hunts for sustenance might also come to treat the activity as somewhat of a sport, or an art, and so come to appreciate aspects of the activity including the intelligent behaviours of the prey.