People prefer big things like a big house, a big car, a big phone screen without thinking about whether they are practical. According to the research, people seldom use their living room and dining room. They spend most of their time in a very limited and fixed space in their house.
People maybe use their guest room, the second toilet only once a month but this subtle convenience is very important. They pursue the comfort more than the practical use living in the big house. The house is divided into the formal space and the informal space. The bigger the formal space, the higher the position and the more space they could entertain their guests.
But given the mortgage, the tax and the maintenance costs, the big house is a heavy burden for normal people.