But really because her acting skills are terrible.

Via Daily Beast:

Scandal star Kerry Washington says she was fired from two different TV pilots for not fitting a stereotype about black women. “Before ‘Scandal,’ I was actually cast in two other pilots. Both went to series, but I was fired and recast,” Washington revealed in a new Variety interview, set to air this month on PBS. “For both, it was because they wanted me to sound more ‘girlfriend,’ more like ‘hood,’ more ‘urban.’”