Actually this does not surprise me. Apple typically envisioned functionality in development that never made it to the release stage. My guess would be that this is the situation here. In the rush to market, rather than strip the software of the code which might have created other bugs, it was simply rendered moot by limiting the signals available on the hardware remote.
I can see some benefit to closing the currently open window if you are working on something with the TV on and get up to take a break and decide to watch the TV from the couch. If there are corresponding navigation signals as well, one could launch documents or applications from across the room by opening the selected disk. Again, some of these commands may not have ever been fully implemented or created problems in development and were ultimately dropped from the final release and never considered important enough to revisit.