Rectilinear Structures are Heavily Favored

 Building non rectilinear structures escalates the cost orders of magnitude. Until recently the math would have been a lot more difficult. Curves are hard for carpenters to calculate. Square footage of various comic sections, how and where to cut, and what to cut with for variegated surface, calculations for interior insulation that’s a reciprocal of diurnal solar exposure, etc are tougher. Building artificial mountain ranges for people to inhabit with habitat for wildlife outside might be easier.

For individuals building complex curvy structures might be more the kind of thing rich people could do. Gunnite spray concrete of course allows complex home structures to go up readily for specialized contractors. Incidentally people with bad knees don’t like stairs.