The drawback in this is the cultural need for privacy that seems to have developed in many modern countries. People want to be able to shut their door, and this interferes with the cross ventilation. The whole "separate rooms on separate floors" also drastically hurts this concept. My house was reasonable, but my bedroom was tucked into the roofline on the top floor. It was unbearably hot, so my brother, father, and I would sleep on cots on a screened in porch.