When I look at pretty old buildings, what sticks out are hand-molded wrought iron, hand-laid brick quoins, hand-carved window siding, hand-assembled decorative fences — surely, you can see the common factor? So it's cost disease. http://en.wikipedia.org/wiki/Baumol's_cost_disease Modern buildings are made principally of prefabricated components designed to be packaged and shipped efficiently and assembled quickly. Wh…
When you look at old buildings you're automatically starting with survivorship bias. Expensive and well kept old buildings tend to stay around a lot longer than buildings that were built cheaply at the time. Those have all been bulldozed.
Oh, did I mention that expensive building was expensive? It's easy to ignore that huge parts of the population were living in houses with paper thin walls and spending enormous amounts of energy to keep warm or cool (on cooling people had avoided the southern united states in mass till cooling options were available).
Oh, did we also mention that not only the US population, but the global population has increased massively since then. All of those processes you're describing are massively energy and labor intensive and do not scale as you're trying to put 8 billion people under rooves.
Why lay bricks rather than fake bricks? So everyone has a home and they don't have to burn an entire forest to get it.