The reason dwarves are known for their art deco angular design is their art reflects their city planning.
It's much easier to be sure you measured right on a straight line than on a hyperbolic curve. Much easier to calculate and map a 3D space carved into solid stone if the ceilings are flat or at measured angles; you don't want to unexpectedly end up with your new street intersecting a vaulted ceiling of the layer below.
















