Why do humans find baby animals like cats, dogs, ... so cute?
As these are potential competitors or even natural enemies (like e.g. tigers, leopards, ..), the protection instinct (reasonable for the babies of your species) should therefore not apply.
I can't imagine any reason why evolution let mankind adore foreign species that much. Maybe only humans liking the enemy's kids survived, because they weren't killed by the baby's parents.
What is the evolutionary reason?