― Terry Pratchett, Lords and Ladies
They are also fairly intelligent. Intelligence can be cute, and the cuteness of intelligence is enduring. Rabbits are cute to look at, but make for boring pets; cats and dogs can fascinate and charm us for years and quickly become considered friends and the near-equals of humans. And don't tell me that a cat who's figured out how to operate doorknobs or lightswitches isn't adorable.
A lot of this has to do with the fact that we are also predators and these characteristics remind us of ourselves (in particular, our young).
Appearance.
> "the way they pounce on and bat at things"
Style.
> "their little fangs"
IMO, fangs aren't exactly a cute feature. Cats aren't cute all the time. This isn't a cute image of a cat IMO, for example...
http://baddogneedsrottenhome.com/images/emails/55c8ce1c28a9b...
> "They are also fairly intelligent. Intelligence can be cute, and the cuteness of intelligence is enduring. Rabbits are cute to look at, but make for boring pets; cats and dogs can fascinate and charm us for years and quickly become considered friends and the near-equals of humans. And don't tell me that a cat who's figured out how to operate doorknobs or lightswitches isn't adorable."
Again, style.
It's possible to see a cat's playfulness and intelligence as separate from its roots as a predator. I don't think we actively have 'killer' in mind when we see a cat look cute or do something cute.
I wouldn't describe our predatory instincts as cute.
Furthermore, there are tons of animals that are not seen as predatory and are still cute. To me they're completely separate traits. For example, which one is cuter to you...
https://i.ytimg.com/vi/LgINvKhd2wc/hqdefault.jpg
https://pixabay.com/static/uploads/photo/2014/10/01/10/44/he...
And it's adorable. I used to tell my parents' kitty "You're such a cute widdwe pwedator, yes you are!". Sometimes while she was playing, other times after watching her hunt and kill a lizard in the backyard. There wasn't much difference between her behavior between those times.
If being a predator was a deciding factor in making them cute, then other predators would automatically be cute too. Perhaps you think all animals are cute, but I don't think of sharks, snakes, crocodiles, etc... as cute.
In other words, IMO it's not what they do that makes an animal cute, it's the way that they do it (and/or their appearance).