Well they do serve a mechanical purpose, since it still affects your hitchance and perception checks ...
I also have to remember to use some source of Light when fighting Duergars ... last time i noticed they HAVE sun sensitivity, when you examine them ... and i wondered why, since there is no way to drag them abowe ground ... so maybe ... ?
I still dont understand why cant we change Race for our hirelings. Lets us play Githyanki as racist as they trully are!