Honest question why are buildings so old and ugly in Taiwan?

I love Taiwan to bits and would come back in a heartbeat. I don't want to be offensive here and am asking out of genuine curiosity. In the big cities apart from the newer areas, the old buildings are super ugly and run-down. I appreciate the climate is hot, humid and it rusts everything and leads to mould/moss growth. But I also heard that many home owners don't want to rebuild/renovate because land tax is determined by the original value of the building and they want to avoid a higher tax that comes with a rebuilt apartment/house. Is that correct?