Champagne is literally the name of the area where the product comes from. It makes perfect sense that anything that doesn't come from the region Champagne, isn't champagne... Call it sparkling wine, it's fine, but not champagne. And it applies to most local products. Camembert? Comes from a specific town, which is called Camembert. Beaujolais? The name of the province. And the list goes on. It doesn't sound "absolutely ridiculous" to me.