The red screen makes watching the channel extremely difficult for a long period of time and almost forces you to have to switch the channel.
I suppose that's the whole point. If they put something watchable on BBC One HD, then regional news programmes would probably lose out on a chunk of their potential audience due to people not being fussed enough to turn over. Auntie Beeb clearly doesn't want that, and probably learned that lesson from the era of "UK Today" on digital satellite.
"...we might find a way for audiences to move more conveniently between HD and SD."
I'm not at all technically minded. If some means exists of triggering all Freeview/Freesat/Sky/Virgin digiboxes that are already tuned to BBC One HD England to automatically switch over to BBC One SD as the regions opt-out, then I'm all for it being implemented ASAP.