I don't understand how this help security. No one knows what email I use to log in. Everyone knows your 'Display Name'. Granted they need to know the security questions, but knowing each persons display name is one less barrier IMO.
no one "knows" my e-mail or my real identity but everyone on these forums knows my username
my mind is conjuring scenes where some butthurt player has a tiff with another and begins trying to hack an account
where 1/2 of the login information is available for the world to see