I have been thinking about this a bit more as well, because you are of course right on principle, people should feel empathy for the other creatures that share our world, and I also believe that most people are capable of empathy in general.

So it must be something else that makes it weird, and the only thing I can come up with is the anthropomorphization of the animals. People might agree on principle that we shouldn’t harm other beings, but might feel uncomfortable with the notion of treating them as fully equal to humans, even if it’s just on a subconscious level.