A thing I've noticed while attending school in Japan was that many old "Machiya" houses get torn down and more modern and western houses get built. At least this was the case in Kyoto. Earthquake-proofing the house is one aspect but I think people in Japan prefer to own a more western home. It's too bad because those old Japanese homes are getting taken down
I agree on that, although there are residential homes in Japan that implement energy efficient outer shell, while still keeping the Machiya look. There definitely is a preference in Japanese society for western style homes.
As a Japanese, I think modern houses in Japan as just a "house" rather than "western style house". That's the default rather than preference. Traditional Japanese style house isn't an option for most people. Cost and insulation would be a big reason.
Most modern Japanese homes are not "western style" at all. They're usually built by large industrial concerns (e.g., Toyota, Sekisui, etc.) that prefabricate many components at scale. The process of building such a home in Japan begins with a company architect fitting their design system onto your lot. The price is fairly predictable, and relatively cheap—-under US$300K in most places. The home is designed with more or less the following priorities:
1. Safety
2. Ease of maintenance
3. Efficiency
4. Cost
And more recently, considerations for SDGs (sustainability goals) with respect to materials used.
Longevity is not a priority, as homes are expected to depreciate in value over roughly 20 years. There are many reasons for this, but my personal opinion is that industrialization has made it possible to upgrade the technology of the home at a pace and a price that favors rebuilding.
As for machiya and kominka, local governments like Kyoto have tried to intervene to preserve the traditional homes. The "no build" lots do not allow a property owner to build on anything other than the load-bearing structure for the old home. As a result, you have many empty lots and coin parking lots around Kyoto where the old home was unsalvageable or where the owner could not afford a renovation. To be honest, only tourists/foreigners would want to stay in a machiya for the novelty of it. Although they were marvelously engineered for their time, they tend to be rough living compared to the extremely easy and cheap prefab homes. There is also the problem of craftspeople who can maintain these old homes dying out, which adds to the cost of keeping them.
I don't think it's possible to attribute any of this to a general "Japanese" attitude, though. On the one hand, one of the most important and longest-lasting spiritual sites in Japan is Ise Jingu, which is rebuilt from scratch every 20 years as a Shinto ritual of renewal. On the other hand, you have some of the oldest and largest wooden structures in the world still standing in Nara.
