1. If regedit is blocked by malware, this is a highly useful implementation, since it would be client side, and not actually use regedit. When a change is made the command could be sent to the server in which case it would call the specific APIs to perform the requested operation
2. Speed. You do have to experience any lag when browsing and typing through the trees and hives
3. Could possibly improve over regedit (such as adding an address bar, bookmarks, etc)
4. Allow you to drag and drop .reg files with preprogrammed operations, to be sent to the server. This would be much easier than having to first locate and send the file to them, and then have regedit import it.
5. Modify the registry when no user is currently logged on
6. Exporting and importing Hive files directly from your machine, instead of having to transfer them back and forth.
7. View & troubleshoot a user's registry while he/she is currently performing some specific task (therefore would not have to take over their mouse and keyboard to change some kind of setting)
8. Back up portions of the registry directly into your machine (the client)