Still way more expensive than just laying cheap, factory-made bricks or pouring cheap concrete. Not to mention, at least in most of Europe, the buildings are expected to be thermally insulated, which is usually done with styrofoam on the outside walls (whereas, in the past we didn't have styrofoam so buildings just needed to have a lot of thermal mass (which in practice meant thick walls), which also made them more interesting and prettier). Placing the ornaments on top of it is not great solution, since the styrofoam has limited lifespan.
