Earlier quoted context omitted.
East coast cities were built before modern building codes. Something that, for some reason, people in the states don't want to accept is that - when given the choice - the vast majority of people prefer living in dense urban environments.
OP addresses that. Japan is not particularly dense, especially outside of core downtowns. You see the same dynamics in London and Paris. People do not "prefer to live in dense urban environments" by urbanist standards. They prefer to live in dense urban environments by North American standards, which can still be far less dense than urbanists really want.
Nobody wants to live there, it's too crowded and there's too much demand for housing! Oh wait, that makes no sense.