japanese houses aren`t insulated

It seems a very obvious thing to say but it also seems a subject not discussed often enough. It strikes me as being even more relevant after the intense heat and humidity of the summer.

The Japanese winters are dry and bring with them the hightened threat of fire. It is the busiest time of year for the fire service, as the majority depend on varied heat sources throughout the house sucking energy resources dry and the atmosphere even drier.
an eerie, traditional bell circles neighbourhoods by night to remind of naked flames and their hunger for timber.

from October the 1st in central honshu, and for 5/6 months (a long time to eschew extra padding), the air temperature drops and many devices are employed to act as deterents to the cold:

O-FURO
hot springs are replectated inside the home and a tiny bath of almost boiling water is prepared nightly for the family to share. The greatest advantage of the family sharing is the economy of the ritual (washing and rinsing take place before plunging). It can be kept warm between users by placing an insulated foil and foam blanket over the surface, and even re-heated the next night if required. you go to bed warm.

KOTATSU
the blanket over the living room `coffee` table which is a heat source and traps heat at the same time. your legs go under this. great for getting cosy, but hard to leave, often resulting in premature sleep/erratic sleep patterns. another `down` side is you don`t know whos feet you are touching.

TOIREI
The toilet. often described as the warmest room in the Japanese house during winter, due to the heated element in the toilet seat. a comforting invention especially in the middle of the night. the old fashioned version before the washlette was a towelled seat cover. questionable hygeine and not as great a heat source.

WARM A/C
hear your skin dry.

KAPETTO
an under carpet heating element. subtle and cosy but again, pretty dry.

PARAFFIN HEATER
Actually, with a steam producing kettle on top, this is a nice traditional feeling addition to a kitchen. slightly high on the danger scale, but has the real flame quality other heat sources fail to deliver.

OIL RADIATOR (movable)
remains warm when switched off. humidifier needed in conjunction.

while these are very interesting and cosy in their own right, do they really provide proper, economical and sufficient heat?

Is the lack of a more integrated heating system and basic insulation not the reason for all the colds, coughs and sniffles that can be seen on an average commute in Japan?