For their own good and safety of course.
To those that say its necessary I say thats what your voter registration is for. If the state want's to prevent voter fraud they can create systems to look for mulitiple registrations and votes. There is no need to further a creeping police state to protect against fraud that can be prevented via less authoritarian means.
Everyone doesn't have a drivers licence and I don't like the idea of needing manditory state ID in order to enjoy one's constitutional rights.