My first take is the maintenance cost. When labour is plentiful and cheap, you can have teams of cleaners to meticulously brush each corner in the intricate roo

My first take is the maintenance cost. When labour is plentiful and cheap, you can have teams of cleaners to meticulously brush each corner in the intricate rooms, corridors and decorations of an Art Nouveau building. When the cost with the labour force rises, you need to clean with fewer people, and faster. You need to use larger tools to cover the same area faster, and the tools require simple large shapes where, a vacuum for e.g. can easily go in any corner - hence a cube. Add the need to build fast and cheap, so concrete is it, or, after technology advances, just metal, glass and drywall - who has time to wait for the concrete to set? - so you end up with utilitarian cubes of cheap materials.