In reply to kristian:
"> I can understand why people get freaked out with just one bolt at the belay. However the belay bolts would never be subjected to the loading of a protection bolt as it is only bounced on by the climber and belayer. "
But, the top anchors and the first bolt are the only ones where you're only attached to a single point and a fall from the first bolt is unlikely to be as catastrophic as a fall from the top. I guess you could mitigate for all these situations by re-clipping all your gear to the opposite rope as you second a route (assuming it's single pitch) and using a prussic loop when being lowered to protect against the anchor failing. But this is a lot of faff and not fool proof.