You could have a setup where the other end of the USB cable is hard to reach so you can use the circular connector to swap the keyboard-side of the cable for a different style USB connector. But then why not just have a USB extender mounted to the desk in an easy to get to spot? You would need to make a bunch of variations of the USB to circular connector pigtails to plug into the main one. Seems like a lot of work for something that usually only takes a couple seconds if you have an easier to reach USB port. If the guy says the circular connector is just decorative, I'd believe him. Nothing else really makes sense.
If there's ever a need for a GX12-to-MicroUSB or GX12-to-USB-A cable, then sure, but I doubt it, and the poster specifically said it was only for decoration.
