The Wikipedia definition seems to indicate it has origins as a racist term and I’ve never understood why unix users have adopted this terms instead of something benign like “themes” or “theming” which I remember being in use long before I ever heard “rice”. So what gives? Why use “rice” instead of “theme”?
It’s from 4chan /g/, it’s been in use for at least a decade there, probably longer
That is the absolute least-surprising explanation.