The cable seems to be needed for certain features, like photo review (quote from the "How do I set up Photo Review" tutorial https://www.foolography.com/faqs/how-do ... to-review/ is below] and better GPS functionality.
Also, when the cable is plugged in to the Unleashed N1, the flash sync port cover must be removed and the port itself is blocked. This, I believe, is the standard configuration for recent Nikons with 10-pin connector, so it isn't unique to the D500.Photo Review for Nikon Cameras
2. For all Nikon cameras this short and flexible cable with small right-angle plug is necessary for the photo review feature.
Perhaps the connector for the USB cable should be on the side of the N1 instead of the top. That way the Flash Sync port is not blocked or exposed to the elements, and the N1 is protected a bit from rain (a rubber cover would also be good, for when the cable is not in use).