I've long had a theory that cats have evolved to be just cute enough that we don't murder them. Cats are evil, so it's understandable that humans would want to kill them, and I think we probably did early on, but some of them were so cute that we didn't. Those surviving cute cats reproduced and made more cute cats, but they also became more evil. Over generations, we have created beings that are supremely evil, but they're just so gosh darned cute that we let them get away with it.
Yeah they evolved to keep much more baby-like features into adulthood with a big head and huge eyes because that's cute to us and triggers strong instincts of protection and love. I forget the exact name for it. And my cats do be looking extremely cute all the time so it was very successful.