My opinion: NO!
Atemi waza in my opinion is about off balancing. Every technique has an implied atemi, but it does not necessarily have to hurt, or even make contact. It is about distracting, or taking balance. The goal of Nage in my opinion is to take balance.
However if contact or pain is what is needed, than that is what is needed. If the threat is off balancing than that is what is needed.
My back up source:
I agree that a sharp kiai or a feint to the face can certainly be enough in the right situation, but you should always train atemi with the intent to hit and hit hard. It's similar to the difference in a karateka training to tap the pads or training to punch 6 inches behind them. One is certainly going to be more effective in a real situation simply because of how he has conditioned himself to use his strikes.