Indeed - quite a lot of stations already have platform staff for checking doors and notifying the driver that it's OK to close. I suppose it would depend on the ratio of active trains to stations as it which is most efficient. I believe TfL have committed to manning all stations after the closure of ticket offices so having platform dispatch staff may be a useful use of labour.

That did occur to me after I posted - someone on the platform would be much more useful - able to directions to people, etc.

Vancouver's Canada Line (fully automated) opens the doors fully and then tries to slowly close them if it detects an obstruction. A similar system could be in place.

They'd probably never close in some stations, like Victoria at rush hour :-)

Yeah there's attendants at every station, they're just not always out on the platforms. I've seen them bitch people out for doing it. There's also announcements really frequently telling people not to hold doors.