It is not just regulations. It is because land + regulations are expensive, cutting costs is important. Now we also could count high interest rates.

So, building as cheap and fast as possible is important to stay afloat. Example: making house from prefabs is cheaper and faster comparing to building using bricks + pro brick laying technics (i.e. what you can call ornamentation).

Besides, we should also consider that while saying that ornamentation is good to have, it does not mean it would fit all the people.

Good idea is to have regulations limiting what exactly you can build in historical centers of european cities.