This is a strange thread. I don't think anyone or any culture can lay claim on "inventing" cute. Babies are cute. Perhaps they are cute so mommies and daddies will take care of them since they are helpless on their own. 

Cult of Cute is a subculture gone mainstream.

Just like the original poster on this thread, I was completely baffled by art I was seeing from Japan. So I did my homework.

"Kitten Writing" in Japan in the 1970s started, apparently spontaneously. Just like girls here do ridiculious "bubble" writing with hearts to dot the "i" and such nonsense, the Japanese girls were doing it. It wasn't easy to write. It wasn't easy to read. But it was popular, and gaining popularity. So "Kitten Paper" was invented for girls write their cute scribbles on, and the mascot was Hello Kitty.

Smart Japanese businessmen quickly realized, "Cute Sells." 

bB