I think what you are describing is what the central bank calls hedonics. They substitute one good for another in the basket of goods used to calculate inflation. Otherwise the inflation figure would be much higher than it is. So instead of solid 2x6 studs in the floor, we use engineered struts. I visited Pompeii, I was amazed at how well preserved all the marble was.
I was surprised to see what looked like restaurants. It seemed like they served food to people walking by. They had a counter facing the road with a hole in it. I could imagine a fire inside the hole, with presumably a pot with food above it.
There were a lot of mosaics that were preserved too.
I saw marble in the temples, a bath house, and in the cemetery.
The roads still had ruts carved into the stone from all the carts that had run over them.
Prior to the industrial revolution most people did not live in stone palaces, and I doubt Pompeii was any exception. The population of Pompeii was 10k-20k people and they were probably supported by one or two orders of magnitude more subsistence farmers living in homes that mostly don't exist today.