I think default/green players(green beans) should be allowed to use the command /realname. They often message me of what others' player names are. Also for /realname proof if needed.
#1st support! I think this is a brilliant idea because sometimes when I want a green bean to visit me, they always ask me "What is your IGN?"
They can't use /realname? That could be an issue if they need to contact a mod, and the mod has a /nick on. Support.
Support. Its easier to know the real names, since typing the nicknames that aren't close to the actual name is a pain in da butt. It will make my life/all greenies life easier.