Quote Originally Posted by Malvolio View Post
It's because, by 21st century standards, Uhura's job on TOS could be done by computer or non-sentient robot. In order to justify having an actual Starfleet Officer in that position, there would have to be more to the job.
While we don't have Radio personal anymore we still have IT who are in charge of communications and maintaining the equipment. The Chief Engineer doesn't fix every problem with the Transporter Room that's the Transporter Chief's job and maintenance of the Comm System would be the Communications Officer's job along with answering and sending communications both externally and internally for the ship.