Granted it is cute, especially when you respond in the same manner that the child you are conversing with does. And we are always surprised when the child responds to our goo-goo's and gaa-gaa's, but we shouldn't be because that's all they know.
So is it the added pressure of our abdomen muscles on our diaphragm that we are unable to talk at least semi-normal to a child? Or have we reverted to some prehistoric homo sapiens' language that is instinctual to our nature? Or possibly have we retarded our communication area of the brain by excessive pressure of being upside down? Now don't get me wrong, I don't mean we should talk to our children like the are college doctorate graduates who have a PhD in English, grammar, and pronunciation (Lord knows if my kids ever get that word smart I am screwed) but why do we do it? Why talk like Taz from Looney Tunes or an illegitimate love child of Elmer Fudd and Foghorn Leghorn?
But I know when I see my son later I will have forgotten everything I just wrote and launch into a audio assault of mouth farts, shrill shrieks, beeps, boops, and baas. All the while be potentially mistaken for a lonely sheppard in the hills of New Zealand dressed like Chewbacca.