Once again, a question has come up on the Bacula users' list about restoring just the registry of a Windows box that has corrupted its SOFTWARE registry hive to the point that it won't boot.
I put it to you that of all the "innovative" ideas that Microsoft has built into Windows over the years, the Windows Registry is the worst. It is opaque, it is fragile, it is difficult to back up, clean out or repair, you can pretty much only repair it from Windows itself which means that it's almost impossible to repair it when — not if — Windows corrupts it, and all kinds of noxious things can be buried inside it by malware. Not only does Windows periodically outright corrupt the registry, but from the first time you boot a new Windows installation the registry starts accumulating cruft and droppings that gradually bog the machine down and introduce cryptic malfunctions with no readily determinable cause. Things that worked yesterday just stop working for no apparent reason.
Combine with opaque hexadecimal-string registry key names created by various things, so that you can't even tell what some random leftover registry key belongs to or whether it's still in use, and it's a recipe for disaster. That disaster has been ongoing for fifteen years now, and there's no end in sight.
The saddest part about the whole thing is that Microsoft actually believed that this massive, opaque, monolithic, unmaintainable monstrosity would be an improvement.