Why do you think Golding never gave Piggy a proper name?
Names are symbolic in this novel. Piggy represents nothing more than entertainment for the boys on the island--rather like the wild pigs they hunt and eat. He is bullied by all the others with the exception of Simon and Ralph, and he is used by the others for what he can give--his knowledge and his glasses which provide fire. Once they are stolen from him, he is deemed as useless as the conch and "thrown away.".