I too feel this way about certain names. It's the nicknames that make me love them, not the full version!
Gus,
Archie,
Charlie,
Louie and
Toby are some names that instantly come to mind. Funnily, I feel more like this about boy's names, not so much girls. There are a couple examples;
Hattie, for instance, and
Eliza, but not as many as the boy's camp.
I personally don't see anything wrong with giving nicknames as full names. I think it's kinda hip actually. Well, in most cases. As long as the nickname has enough strength to stand alone. I would feel pretty sorry for a little girl named something like
Missy or
Prissy. The name has to has some weight to it.