No, they are extremely well-attuned hunters - their bodies have evolved to hunt efficiently and almost silently. They are following instincts instead of actually selecting "ruthless" or sadistic" behaviour. In their native habitats, they are a healthy part of the ecosystem that helps keep other pest populations in check, particularly rats and mice etc.
They are not native to Australia and are not a natural part of the ecosystem, so the dynamic is thrown off. It's sad it's come to a mass cull, but the natural members of the ecosystem have to take precedence or else it'll be off-balance going in to tha future, causing harm to natural dwellers.