"I don't like when people hold a piece of paper, especially actors, because we memorize lines for a living. You think you could come up with 20 names."
~ Emmy nominee Neil Patrick Harris on "Ellen," speculating about possibly giving an acceptance speech
While I agree that actors memorize lines for a living and it should be easy to memorize an acceptance speech, in the moment of winning a coveted award it could be just as easy to forget everything you wanted to say. Not everyone thinks quickly on their feet and someone who wants to speak from the heart may end up with a blank stare on his face.
Just a reminder: it's entirely up to you whether you want to use notes or not. Just don't let anyone tell you that using notes is not okay.