No atemi = no technique, for either Uke or Nage
damn - I knew I've been doing something wrong... the problem with blanket statements is that 90% of the time they're wrong!
Joking aside, I'm with James on this one. Certainly my atemi (= strike in this case, not the notional body versions) are limited, with training generally involved more with blending with what is given than imposing a particular technique. Atemi in a static or "dead" situation/grapple to create movement, fine. Assigning the term atemi to the initial cut/parry e.g. in a tenchi-nage, also fine, but as a straight up I hit then do technique, nope, but that's probably just me.
One of the problems I have with the notion of the single strike then finish is the same one alluded to by James. People can take a hell of a lot more damage than you'd expect and I've known one or two people who can and will quite happily eat a single punch or so to get their grubby little mits on you before tearing you apart like rice paper. Now as I've not seen any ma based on striking claim a 100% success rate with a single punch, the idea that most aikidoka have it is slightly strange.