Aikido has many ways, and depending on person and style atemi will differ. I've done styles without atemi, and styles with alot of atemi.
You state that most of the techniques imply to catch the arm.. nope is my answer to that. If that is what you got from training aikido, your barking up the wrong tree. Aikido doesn't imply.
/Terje
Nope? Ok. Because that´s what i´ve always saw Aikidoka doing: Catching arms in movement. Your style must be different.