they are cuter than chibi to be honest desu senpai-senpai
It's more associated with carnivores
Humans' brains' grew from eating meat
So, basically, you're attracting a female to come eat your cock, that way her brain will grow more and the future generations will become smarter
it also denotes a physical flaw in an otherwise physically perfect specimen. We are used to human beings having flaws, even beautiful ones, so anyone with no flaws is in the uncanny valley.
I want to rape her, and watch as she cries out for cocunuts to save her, but her calls go unanswered and she has to cry all afraid and alone as i plunge in and out of her like a jackhammer.
Actually it's the for the same reason you find chibi cute.
A mouth with just a fang like the way it's represented in the OP is usually seen on babies/children who just had one or two teeth grown. And you're conditioned to protect/find lovable this sort of thing.
And it's the same as chibi because huge eyes are also a characteristic of children since their heads are smaller.
Dunno why we also find it sexual attractive instead of just "fatherly cute" , perhaps all men are pedophiles or something.
It's not that, it's a symbol that represents the way some people open their mouths. Which gives them a rogue-ish or aggressive vibe. A lopsided snarl or grin is a lot more "rebellious" or "lively" than a symmetrical one.
It's not literally having one tooth or one tooth being bigger than the other. Toothlessness and any asymmetry there are actually incredibly repulsive to most people.