I think rotties have an aesthetic appeal due to the structure of their faces. I know that humans have used eugenics to breed dogs to have specific traits and one of those "creations" is the puppylike dog. This puppylike quality is said to cause us humans to go all goo-goo, which I think is true.
I see that in my rotties, particularly Betti. Greta simply has an endearing face and an aloofness that makes her attention something that is measured and, therefore, hard to come-by. Makes me appreciate it even more. But the look in Betti's big eyes and the way they are set on her puppylike bubble head with her cute furry snout...it's just adorable.