A lot of us or some of us have a a lot of friends on our list and at times we also have others where we don't remember who they are or we cannot pronounce their actual nickname, anyways there's other reasons to why the ability of adding a Nickname would be nice, we could put info on the nickname, or their actual name or something else to know them as, and it would show up above the name tag or somewhere else but in a smaller but readable form.

Not something big, but a small detail that can come in handy :D