They have taken down the railings at Vauxhall Cross and it doesn't appear to have made pedestrians fling themselves into the roads any more frequently. It's also useful for cyclists since they have an escape route should a motorised vehicle (high sided or not) cut the corner - with railings there is little chance.

However, I agree that given the size of the island, removing them without considering a proper redesign is foolish. Pedestrians are second-class citizens going through Forest Hill and it's ridiculous that those trying to get to the station have to wait multiple phases to cross a road. They deserve equal consideration and a pause in the traffic so that they have priority across the full junction (as Foresters says like Oxford Circus). Yes, it might delay drivers a little - 30 seconds or so - but as drivers are a minority in London, why should they take greater priority?