"Mammals (at home)" is a response to how people actually occupy their family room. Rather than always sitting on the seat, one might perch on the armrest. One parent may sit up straight while paying attention to the television while their spouse snuggles in close. One kid might flop out on the floor while another might be panting for attention.
This furniture puts the "living" into "living room". Through their example, these furnituresque objects invite human residents to join them in relaxing. (And "Mammals" can watch television programs for you so that you don't have to!)