Lit, I understand what you are saying about destruction of old buildings.
However, cities change. The buildings of the past aren't necessarily suitable for today's needs. The old building you (collective you, not personal) want to keep may have replaced an even older building that had some significance or use. As much as I love old buildings I reluctantly realize that progress is here to stay.
Lest you think I'm being argumentative, I prefer buildings to people. A building just seems more reliable than people, in general. And I prefer old homes (separate rooms for separate functions, woodwork, the comforting creaks) to newer homes.