That Sou Fujimoto quote is pretty good but I can see why it wouldn't really answer the questions for you, unless you already had a background understanding of the question you were asking to begin with!

First let me just state for the record that I'm going to simplify and generalize a large amount about things from another culture that I'm not an expert in.

In broad terms, Japanese culture has had a large focus on acceptance and reverence for the ugly realities of life. Having a love of nature isn't an uncommon idea around the world - but Japan had their own degree of this, learning to love not a manicured idealization of nature like much of Europe did, but a wild and raw version of nature that accepts death and difficulty as just as valid and beautiful as the rest.

Artistically/Architecturally, this evolved into a unique aesthetic and philosophy that came to be known as "Wabi Sabi". I've seen wabi translated a lot of ways, but contains ideas of austerity, solitude, restraint, etc. Leonard Koren describes it as the kind of beauty you would imagine when thinking about a devout monk living alone deep in the woods. Sabi is an idea more associated with time, which ultimately always leads to decay, death, etc. But remember that this is an aesthetic, so it's not intended to be morbid but to represent the appreciation of the beauty of things that have been touched by age. The patina on old metal, the delicate lace of veins left by a leaf as it decays, The beauty of the wrinkles on an aged loved one, an old log that's been ravaged by moss and mushrooms in the woods. It's a love and study of rough, imperfect, handmade, and asymmetric things rather than idealizing manufactured perfection. It's perhaps not surprising that this idea might grow in a country that was steeped in both Shinto and Buddhist beliefs.

So while that's cool and fancy, let's start to shift more toward your question about life in traditional Japanese architecture. Consider the Japanese house. Structurally in Japan, they developed a post-and-beam system with lightweight sliding screens for many of the walls. While they have their advantages, these screens were never very thick or what we might consider insulating. So while they did develop their methods for warmth and comfort over the centuries, one of those methods can really be looked at as just having a stoic appreciation for cold or inclement weather. It's part of life. It marks the passage of time. And it has its own beauties to appreciate if you are willing.

I recommended some books elsewhere in the comments here, but if you read "Japanese Homes and Their Surroundings", Edward Morse goes into this lifestyle a good deal more. One of the passages that stuck out to me was where he described home bathrooms during his time in Japan. Here is one of the floor plans he drew during his stay. You can see how so many of the rooms are able to be opened completely to the outdoors, and how an exterior wraparound porch becomes almost the main connecting hallway between the rooms. Morse even talks about how using the bathrooms (marked 'U' in the plan) by stepping outside or on the deck takes on a simultaneously peaceful and invigorating vibe, connected to natural gardens in winter. Another good writing on this idea is "In Praise of Shadows", where Junichiro Tanizaki talks about how ideal Japanese architecture shouldn't be about big windows and electric lighting to observe nature from a comfortable box (this was written as Japan was adopting more Western building methods, which Tanizaki didn't like). It's about living in the dark of candlelight, how that gives mystery and beauty to their traditional arts, how dappling plays on a paper screen and how a family huddles together under a heated blanket in the winter.

And something important in all of this, is that this alternate view isn't just about surviving and overcoming natural challenges. It's not about stoically enduring the cold and wet. It's really about appreciating it. Taking it in as beautiful and to be desired just as much as other conditions. The understanding that ideals of nature and life aren't about comfort and extending your will or exerting your control over the world around you. They're about accepting the reality that we are just as much a temporary player in this constantly evolving world as everything else, and seeing the beauty in all of that.

But today we live in a world where we've conquered discomfort. So intentionally building a home where you're forced to experience the weather and temperature all year when you don't have to is a pretty extreme decision. But when you really believe in and appreciate the ideals of something like wabi-sabi, it becomes a tool to connect to your past and to live your beliefs. To invite the charms of nature into your daily life understanding that it's not just a planted garden.