Ascetic Aesthetic: Used in a few types of places:

Unprogrammed virtual reality, as a baseline to build on.

Areas principally given over to industry or other automation, where simple, polished geometric shapes, curves, and suchlike (see: Alien Geometries) work well for the local AI; they don’t care about the lack of decoration, and it can still be kept adequately, for which read exceptionally, clean and shiny-bright.

In some areas, like the Conclave Mall – the central area of the habitat that houses the Conclave of Galactic Polities – intended for heavily polyspecific use, as a reasonable compromise to avoid having to try to satisfy everyone’s differing aesthetic tastes simultaneously.  An equally sparse minimalism is about what can be managed by way of fairness.

The Imperials generally don’t go much for it at home, except maybe in pre-customization prefabs.  They prefer their elegant-baroque art deco style and its offshoots.