I recently read what I think was probably the best descriptions of atemi in aikido in Ellis Amdur's book, "Dueling with O Sensei." In it he references O Sensei's quote that "aikido is 99% atemi," and that it also relates to why an uke should follow the technique. Basically, he described aikido techniques as being a continuous spectrum of potential atemi - that at any point in an aikido technique, there is a potential atemi for nage against uke. Therefore, this is the reason that uke should diligently follow the technique, because if uke tries to divert from the "path" of the correct ukemi, there is the possibility to unnecessarily expose himself (or herself) to a potentially harmful atemi from nage. Mr. Amdur suggests to try stopping at different points during techniques to determine what and where the potential atemi is. To me this is consistent with the common consideration of atemi as a tool to influence uke to move a certain way. Yes, it can be harmful, but it doesn't have to be. Two nights ago the instructor demonstrated this to our class with me as uke. I guarantee you that I could feel the underlying focus, control and power of his tsuki atemi to my floating ribs during the technique.
Also, Jim23 I agree with others on this forum, and suggest you tone down your statements a bit. Yes, some people don't focus on atemi in aikido (especially as beginners), but making blanket statements about what you see after only a few classes isn't going to hold much water. It wouldn't hurt to "empty your cup" a bit before you draw such strong conclusions based on your experience with other arts. IMHO.