Check out Brent Hull on YouTube who is answering this very question. His basic premise is that post WWII the focus on efficiency and mass production ruined the craftsmanship that went into older buildings.
I love Brent and his redesigns of existing buildings are really eye opening. It really shows how bad people fail at building traditional buildings today. He makes a compelling argument for why his redesign makes more sense and to my eye the buildings tend to look much better and simpler too. It's based around some basic theory that had served builders well for a long time and has been thrown out to build gaudy things that imitate very poorly.
One of my favorite observations of his is that a modern cheap door isn't even really a door - it's more a simulation of a door than an actual door. It is made of plastic and filled with foam but is made to look like wood and has stiles and rails and fake paneling pressed into the moulding to look like what people think a door looks like. And it comes in a pre-fabricated frame and is installed, not crafted. But it doesn't feel like a door or sound like a door. Just a flimsy thing that closes a passage off. And we admire installers today, not craftsmen.
One thing about him, and I think he acknowledges it, is that efficiency and mass production are why so many more people can live in relatively nice homes today. Not everyone (in fact most people can't) can live in a well crafted home made from the best materials, etc. But I do agree with him that developers could at least try and make things that are rooted in some sense of design principal.
