EEEEEEE... why do we do it?

I was playing with Brooklyn the other day and realized that everything she was pointing to for me to name, I put an "eeee" sound on the end. Dog is now doggie, horse is now horsey, pig is piggy, duck is ducky, blanket is blanky, cat is kitty... you get the idea. Why am I doing this?! Are kids attracted to this "eeeee" sound?