The key word to note is 'kindchenschema'. It's a word invented by zoologist Konrad Lorenz, who had a rather unfortunate World War 2, though not as unfortunate as many of the people he encountered. He was hoping to get into motorcycle maintenance around that time, something not directly violent, but was instead assigned by the Nazis (his studies to that point had led him to believe there was something to eugenics) to evaluate, long story short, reproductive ability based on racial concerns and, by extension, who got shipped off to concentration camps. He was taken as a POW by the Soviets shortly after arriving at the Eastern Front in 1944 and, really, that was just fine by him. He basically spent the rest of his life apologizing for his role in the Holocaust, even after he'd been forgiven enough to earn a 1973 Nobel Prize (shared with Niko Tinbergen and Karl von Frisch) for much more productive things, namely pioneering ethology, the study of animal behavior. By the end of his life, he had aligned with Austria's Green Party.
You can see in Lorenz's Nobel lecture (PDF) that he had learned some hard, hard lessons from his World War 2 years. He closed with this paragraph:
"Between the conservative representatives of the “establishment” on the one hand and rebelling youth on the other, there has arisen a certain enmity which makes it difficult for each of the antagonists to recognize the fact that the endeavours of both are equally indispensable for the survival of our culture. If and when this enmity escalates into actual hate, the antagonists cease to interact in the normal way and begin to treat each other as different, hostile cultures; in fact they begin to indulge in activities closely akin to tribal warfare. This represents a great danger to our culture, inasmuch as it may result in a complete disruption of its traditions."I think I've pretty much sucked all the cuteness out of this article now. You're welcome.
Anyway. Kindchenschema basically means features not unlike that of a baby. Big eyes, big forehead, rounded features. This is the most effective kind of cuteness. We are, as you might expect, naturally hardwired to be protective of our young. We're more careful, we're more loving, we don't want to hurt the baby. Anything that is physically reminiscent of a baby, puppies and kitties included, is kindchenschema- baby schema- and evokes the same cooing, protective emotions. (Why are big eyes evocative of babies? Simple: your eyes don't grow with the rest of you. You're born with the eye size you're always going to have, so while you're a baby, your eyes are disproportionately large to the rest of your head.
Every once in a while someone looks into this, often invoking Japan and their culture of kawaii, aka deliberately making things as cute as possible. The results of studies done are rather resilient, namely awwwww lookit the cute widdle babby i just wanna eat you right up yes i do!
With one exception: if you're being directly reminded of how you're acting, you can be snapped out of it. The Fast Company article cites (PDF, Page 13) an experiment run by Gergana Nenkov of Boston College and Maura Scott of Florida State in which subjects were shown a normal cookie and a cookie with a cute lion face on it. As expected, the subjects shown the lion cookie were less inclined to eat healthy after that when they were told they came from "The Cookie Shop". But when they were told the cookies came from "The Kid's Cookie Shop", the effect dissipated.
So there is such a thing as cute overload.