Because some people have preferences for certain ethnicities, and putting yourself into a certain group means people can search for that group and find you more easily.
Yesterday there was a rant here about how people shouldn't prefer to date members of certain races, but the reality is that people do. (Next thing we know, we'll hear that it's unfair to only date people of the opposite sex. "Excluding 50% of the population is barbaric!" Only on HN...)
Because some people have preferences for certain ethnicities ...
I should note that my question was more of a thought exercise, somewhat rhetorical.
Only on HN...
That's ironic. As intelligent forums go, HN is probably the easiest place to get bashed for arguing that diversity is useful, tolerance is a virtue, or that racial bias exists. It's a practical guarantee that some wannabe Objectivist will come out of the woodwork to claim you're being too politically correct if you believe any of those things.
Besides pure looks, I think it's somewhat of a proxy for a set of culture/background elements that are hard to capture. There are explicit ones like "religion" and "interests", but then there's sort of a vague, "what sort of community did you grow up in?". Sometimes something other than ethnicity dominates there, e.g. if you grew up in a Mormon community, or a socialist commune, but for many people ethnicity, for better or worse, correlates pretty well with similarity of background/experiences.
