OK, sure. They're cold-blooded killers. But so are we. Farming is nothing but killing once you've planted the seeds. Ants, voles, field mice, crows, invasive species, they're all the enemy of the one particular thing you wanted to grow.
Nature doesn't care, but kitty does. So do we. It's why we have them. The dogs are to ride herd on them because unlike dogs, cats can't be trusted.