You can't just import the foreign culture without the environment that justify the culture.
In Japan, the land is scarce and fragile, humidity weather, constantly facing earth quakes, typhoons. So the house will be damaged faster than the typical western countries.
Each time we face the massive earthquakes, the house building regulation will be updated to mandate new and improved earthquake resistant structure so building built with old regulation lose market values. The same goes for all disasters like tsunami, flooding, land slide and all.
You must also consider the fact that air conditioning wasn't popular 30 years ago. The houses built before that era were optimized for the natural ventilation. it's totally inefficient for the air conditioner.
Old houses also has the Internet issues. Most of the house in Japan are massive condominium. The optical fiber was a thing after 2000s. It takes a lot of money to wire optical cable inside the existing building. So most of the buildings in Tokyo are still using VDSL.
Other infrastructures like power line, water and gas starting to rust so it must be replaced. The cost of doing that to existing house is expensive in Japan and it doesn't increase the value of house that much. Especially for old houses that need replacing because it had gotten so much damage from humidity, earthquakes, typhoons and remember, it was built before the current housing regulation for the resistance for these. So it's more reasonable to just scrap it and rebuild it.
I am living in a standalone old house in Tokyo unlike most of the people. Then, I realized the value of condominium in Tokyo. It works as a gated community, the segregation based on income. We are implicitly achieving the segregation by the condominium.