So you've got yourself a dining room. Congratulations. But it's not really a dining room until you've got a dining room set, is it? It's just a space with walls that happens to have a relatively close proximity to the kitchen. What are you going to do, sit on the FLOOR? Eat your food off the CARPET? Yell at your family in a GENERIC EMPTY ROOM?
Dining rooms date back to hunter-gatherer times. At one point, early man would use the same area to eat, sleep, and defecate. This resulted in massive cases of sepsis, which in turn nearly lead to the extinction of the human race. Faced with the possibility of species eradication, humans adapted, and the dining room was born.