Black and proud of it...

Lighter coloured skin is considered to be more attractive CMAT. Just don't get it myself. It's not a particularly good idea because long term use of bleaching agents can damage skin structure but people naturally want to be considered more attractive.
Look at all the money raked in by the cosmetics industry including cosmetic surgery and tattooing.

Historically, it's actually the case the world over Foinavon, but not 'black/white', rather 'dark/pale'. Dark skin implies time spent under the sun working, whereas the elite didn't need to, and thus their paleness was a mark of their standing, much like obesity in some cultures.