Why even limit ourselves to a binary choice? Back in the Windows 9x and earlier days, you could individually color every class of thing on the screen. Window backgrounds, title bars, scroll bars, buttons, text for this, text for that, everything could be a different color if the end user wanted it. How far we have backslid where offering just "dark" and "light" is now seen as some sort of favor to the user!
We should return to those great days of end user control. "Sensible defaults, but easy to override." Why can't I easily (without writing code) configure HN's background and text color, just through my browser's configuration UI?