I guess it depends on the nickname. I love
Mindy,
Romy,
Edie,
Effie,
Lise and
Lola as legit names. I have a friend called
Gary and his nickname is Gaza. I think Gaza would be cool as a legit name, too. But things like
Fifi,
Kiki,
Gracie and
Prissy just don't feel like proper names.