I realize that is two months late, but baby talk is VERY helpful in developing language, which is one of the reasons why you see it as pretty much universal. Take a look around and tell me if you see this: children will automatically simplify their speech when talking to younger children and pets (who we also think of as children.) Imagine yourself learning a foreign language. Everything sounds as if it’s going by too fast, and you can't tell where one word ends and the next one begins. You wish that those folks would speak more slowly, repeat what they say, and use fewer words. That's what "baby talk" does. It makes speech more comprehensible.