Well think about how much money it would cost to build a house entirely out of marbel or various other structural materials they use to use. Plus think about how uncomfortable it woudl be and how long it would take to build.
Thats one thing thats great about Catholicism though. We have built a hell of a lot of incredible structures. Theres a church nearby I use to go to. Its only 100 years old but its still a great structure compared to everything around it. Theres a new church uptown that rivals our city hall in size and is far more awe-inspiring then the city hall (and the stupid city hall looks like an alien space ship.... funny story behind that). Don't know what religion is there but its pretty big. But of course, the hell if I could ever be in these places for more then 3 hours a week. Cold... kinda intimidating if your alone.... uncomfortable... but i love the organs!