Like the guy or gal who realized that donut holes might be a marketable product (and tasty too!), Mr. Neutrik and his band of connector elves noticed that all of those unconnected connectors were a market yet untapped.
The solution? The dummyPlug.
This is a rubber plug designed to cover Neutrik SpeakOn and PowerCon connectors. Besides keeping dirt and liquids out, the dummyPlug can help in keeping wiring schemes consistent by closing off unneeded and incorrect connectors.