Arkait, I believe that was a good move, as when we trade the brokers will be again totally responsible for their broker generated IOU'S, those holding certs I believe could be left out in the cold, if brokers choose not to accept them back.
You totally lose liquidity when holding certs,not always a good place to be IMO.
Those that hold them now might start looking around to find a broker that accepts them back, sometimes stocks move faster than some can act."Be prepaired"
(Just a thought)