Why are brown skinned people in the black community ignored compared to light and dark skin?

Seems like so many people are always saying something about light skin (Rihanna, Alicia Keys, Jordan Sparks) or dark skin (lauryn hill, whoopi goldberg, taye diggs). The brown skinned complexion (nia long, sanaa lathan, gabrielle union, janet jackson) just never really seems to be addressed or noticed too often.