What I'm trying to learn from my Sensei is to use the Atemi as a tremendous power present all the time during a technique but never used to hit the partner. I don't know if it could work in a real life situation, but if it could then I would concider it a true application of Aikido. During practice with my Sensei it seems to work all right. He can make very subtle changes in his posture and attitude that suddenly makes a world of difference to me as Uke and completely removes my commitment to hit him.
Maybe I'm not making a lot of sense here - just babbeling. To put it another way: I think Atemi should be very strong but the power should be redirected into movement and only be used to strike the opponent when absolutely nothing else is possible.
Hope you can use my answer