I've been using endearments instead of names for the people I love for most of my adult life. My grand niece and nephew (then 6 & 7) wanted to know why I called them "Darling Boy", "Sweetness" and other terms of endearment.
My answer was that when I call them by a love name I can't be angry with them.
It also makes it easy to avoid going through "the list" of all possible real names when you want to address one of them!