As one of those who emerges from Dartmouth Road in a car, I agree that the pedestrian crossing is dangerous and an accident waiting to happen - the number of pedestrians can really build up and inevitably they start trying to beat the traffic when drivers (sorry) have the right of way. Perhaps the period allowed for them to cross should be longer?
The main problem with the Dartmouth Road exit is drivers blocking the mouth of the road en route up the South Circular. Sometimes the traffic builds up a long way back down Dartmouth Road and only one or two cars can squeeze out (if at all). Also, drivers block the entrance to the station which means cars come to a halt approaching the pedestrian crossing.
Perhaps more use should be made of yellow boxes to deter this behaviour. "Keep clear" seems to be frequently ignored and unfortunately some irresponsible drivers get very impatient and vent their frustration by driving too fast across the junction thereby playing cat and mouse with the pedestrians.
An underpass would be great but doubt there's much chance of that.