That choice during registration is a generic question, but that feature is not turned on because we value the privacy of our members. Any member can be contacted using the Private Messaging system. Your profile allows you to enable email notification if you get a private message.
If you look at someone's profile, you can only see their first name for the same reason...
Full names are required for registration, as are the real email address to allow the admin staff ( that would be me...
) to be able to contact you off-forum.
If you wish your email address to be visible at all times, you may place it in your signature block along with your name.