As some of you know I feel very strongly on this matter!
I am totally against Driver Only Operation, it's the cheap and nasty way to operate trains started by BR (on the mainline), especially NSE in the 80's and 90's with the introduction of 319/321 types and Networkers.
The time savings with DOO I'm sure only came about when the current guards procedure came into place? The whole stepping out onto the platform first before opening the main doors and making sure you stay on the platform till the main doors are closed then getting onboard and ringing the bell. Wasn't the old procedure to start the train just the guard ringing the bell once or was it twice? And the drivers would be the train moving off? Correct me if I'm wrong please.
In Japan pretty much all trains on any routes: Local, Regional, Long Distance and Shinkansen all have guards who operate the doors and make announcements and only have revenue duties on the 3 latter types of service. All of the JR routes in Tokyo have guards.
The procedure (On JR East at least) there is to see the train in with your head out of the drop down window in the cab door, check the train is in the platform (there is a painted marker on the platform edge and if lined up correctly the guard can open the doors straight away as soon as the train stops. Then he/she will open the door, stand on the platform and if provided operate the train ready to depart melody that plays a melody on the platform itself along with a final automated announcement to tell passengers that the doors are about to close. Then the guard will get back into his/her rear cab and with his/her head out of the drop down window and observe the platform train interface using moniters located at the rear of the platform if the train is long or the platform is curved. When departure time is within seconds the guard will close the doors then as soon as the doors are closed the train sets off, the guard will see the trian out fully with his/her head out of the window. I am not sure whether the driver goes on the pilot light or whether the guard has to press a button to illuminate a light in the drivers cab because there are certainly no bells or buzzers used for dispatch on JR East operated trains.
I cannot see why that procedure or something similiar to that cannot be implemented here, it is just as quick or quicker than DOO, safer, keeps people in work and a good image to passengers by having more than one member of staff.