I believe this would be more of a personal use program, not to be shared with others for reg exports though. There's programs that do already exist out there for such a thing, and which are useful actually. If you can't boot into your computer, and it's due to a corrupt or bad registry change, then perhaps you have reg exports saved to C:\REG_Bakups? Invoke the program, and maybe you make it a command line utility so that you can send to %1 the path to the registry export to merge with the registry currently on your computer to revert changes? :)
Perhaps it's to compare any changes that have happened to your registry from ____ up until _____ to see if there may be any possibly malicious entries in there for bad viruses or files on your computer?