What about the ability of accessing and managing the library (Importing, Tagging, Renaming, Dragging'n Dropping, ...) simultaneously from any PC at home (or outside home)?
Maybe with an actual Client - Server system, with full control of the Data Base from the client side based on User/Permissions policies . Just like in many companies' systems, where DDBB are stored in the Server, usually located in a separate room and only manipulated by the IT's for maintenance, and data are introduced and accessed from the client work stations. I would reproduce the same scheme at Home, with my HTPC being the Server, hidden in a cabinet by the TV, even without physical keyboard or mouse, where Data Base would be stored and managed from the rest of the Client devices (Laptops, PC's, Tablets, Phones...).
Or maybe with a Web interface (call it WebTag as an addition to WebPlay and WebRemote) also based on User/Permissions policies, with the ability of editing the Data Base (Importing, Tagging, Renaming, ...) from any other device.