The idea was that the change would be an improvement, with better tracking of unread threads. Since most people don't see it that way, the original behavior has been restored.
Sorry for the disruption, and sorry kcbrown and everyone else who liked the change.
Imagine a pathologically idealistic, anti-religious, culturally-relativistic, iconoclastic, socially-irreverent, sociologically-progressive signature line here. Or don't.