I can't speak for that person, but some thoughts:

There's also the Apple aesthetic (white or polished aluminum), and its variants with wood accents and other "luxury" materials.

There are various industrial and cyberpunk aesthetics with exposed metals and visible mechanical parts.

Some people like non-lit solid color options (besides black and sometimes white).

There'd even probably be a market for high-end parts in ugly '80s beige. Not me, but I think it would exist. (see: Noctua fans.)

Case, RAM, fan, and watercooling designers are offering most of these options, but motherboard and GPU designers are stuck on "black and white with RGB."