What are the main reasons for the change of industrial landscape and the protection of industrial heritage in developed countries?

First, please refer to the discussion on environmental ethics in Silent Spring and Death and Life in American Big Cities

Second, industrial buildings are often spontaneously transformed by artists because they have strong aesthetic value. Its long span and solid structure have also become the reasons for its retention and reuse. The industrial heritage is the legacy of industrial production after the industrial revolution. However, under the wave of "retreating from two to three" in today's industry, some heavy industrial plants that produce pollution and consume energy have to be abandoned. However, we can still see the continuation of the spirit of industrial mass production from the slogan and simple and heavy appearance of the old factory building. For many people, these are indelible and must be preserved.