This can be automated, also you can deny certain domains such as hotmail, Yahoo or gmail.
My suggestion is that if you guys are so upset about it you need to contact admin. There is nothing the moderators can do about it. If admin has a solution perhaps it could be implemented.
And as far as Yahoo, Hotmail, etc. email addresses being blocked, as Barry said many use these emails as their primaries, including myself. So it's not a viable solution.