[jlawson]

I actually thought of both of these and discounted both. Here's why.

Post-WW2 buildings in Japan were crap so I can see why they'd replace those. But I think recent buildings are a lot more long-term. My sense is that they replaced because of the post-WW2 cheap building boom, not because of the climate/mold. It's no warmer or wetter than many places in America, and northern Japan is quite dry and chilly.

For the "never bombed America" argument, I'd just point to Europe, which was bombed. Or to new American cities built 1950 onwards, which suffer the same problems. I'd also point to Kyoto, which wasn't destroyed in WW2, but is still functional in terms of real estate AFAIK (though I'd love to hear otherwise).