[Schmitti]

Well, dark surfaces absorb more energy of the incoming light than light surfaces, emitting it as heat afterwards. But this is about reflections; it's a perceptive phenomenon, I believe. If you have a glossy or semi-glossy surface the contrast/difference between surface tone and light reflections is greater with dark casings than with light casings. Many people using tablets, glossy MacBooks etc. have complained about this effect, especially under high environmental lighting levels. And you need higher lighting levels with eInk screens.