Deep sea fish play on on the "creepy AAAUGH" threads of the human psyche in the same way that puppies and lemurs play on the "cute AWWWWW" threads.
Big heads and big eyes and li'l button noses and other neotenic features on the one hand; big heads and big eyes and BIG EFFING TEETH on the other. It's the Uncanny Valley, amped up. Instead of being merely a deformed, "wrong" version of a human, we register angler fish a deformed, twisted, versions of babies, with teeth and fangs that promote fear reactions.
I could go off on a Freudian tear about how that triggers anxiety about how one's offspring will symbolically devour one's life and individuality, by directing the selfish self-directed energies of the ID into something Other. I could probably back that up with a Jungian discussion of similar threads appearing in folklore throughout the ages, in culture after culture.
Instead, I'll just sum it up by saying that ANGLER FISH ARE EVIL BABY CHANGELING DEMONS.