Kotaro Iwano comments

1) Because Japanese prefer little spot solutions for symptoms rather than fixing the root cause. That little fan heater you quickly switch on when you return to your cold house gives you the feeling of control, and that your actions are leading to a better world.

2) Because comfort is only appreciated when there is discomfort. The glorious toilet seat is only warm because the house isn't. The Kotatsu is only cozy because your house isn't. That Hokkairo is only a blessing because of you chose the wrong clothes.

3) Because you should accept what you cannot change. You (most often) cannot choose your house or do something about it. Only very few actually build a house to their specifications. Landlords don't pay the energy bills, so they just want a cheap construction and most houses are glorified yurts.

4) Because it would take away the opportunity to be a great host by overheating the house to 30 degrees Celsius upon arrival of guests to show your hospitality. How would anyone know you are trying hard if there aren't heaters to switch to max (=guest) mode.

5) Because that's all most Japanese know, and you can't want something you don't know. If you've ever lived in a comfortable modern house overseas, you know that the quality of life in a Japanese home in many aspects is simply sub-par. But if you haven't, it all you expect.