They have been wanting to fit these for ages for the broadcasts so people can get an idea of how hard it is to see (useful for stewards when drivers cliam they didn't see something *cough hamilton cough*). Would be cool if they do officially add them as another camera angle.
the Champ Car series had a "Visor Cam" back when it was running, though I HAVE seen one from the 1989 Birmingham Formula 3 Superprix. Still, love these camera angles.