Pot Fillers are a simple concept, just a cold-water tap which can reach the stove top. They are common in commercial kitchens so the chef can fill large pans without the need to waste time carrying pots back-and-forth from the sink.
Do they have a place in the modern, domestic kitchen? They are certainly a luxury item. The cooker is never far from the sink in a well designed UK fitted kitchen and time is less critical when cooking for the family. But they are not a complete waste of money. Pans of water are heavy and pot fillers certainly makes life easier. They also look good, like the one below from Waterworks.
And after all, what is life without a few luxuries?