I've always been curious why O Sensei / Kissomaru / Saito didn't think it was worthwhile to include that.
Because osensei wasn't doing Kashima shinto ryu. He used some old forms as tools but (in his mind) included
aiki in the forms and made up new ones to augment the old ones. It was ALL about aiki for Ueshiba. Therefore: "This is how you would do that WITH aiki". Not about fighting techniques. That is why if you're going to do bukiwaza as part of you aikido training then you better know how it should fit in, and be consistent with your empty hands forms.
What actually is interesting to me is the talk about aiki lately, found at these forums and elsewhere, as a form of internal training/power and how it is different from the standard aiki (of timing and blending type also referred to as ki no musubi - tying your ki with that of your partner). However, it's quite clear to me (and Saito M sensei talk about this as well) that the aiki of aikiken, as bequeathed by the founder, was not so much of the former kind (IP) as that of the latter (ki no musubi).
So that when the founder stated: "This is how you would do that WITH aiki" the aiki part would be basically the difference
in what you see between ichi no tachi of KSR and Aikiken (Saito); i.e essentially how you control openings (and how you are without openings!) thereby completely negating all attacks except the one you intend to draw out. In that way you are in complete control of time and space and in fact transcends time and space and concepts like sen no sen, sen sen no sen or go no sen, It becomes a matter of instant victory (masakatsu agatsu katsu hayabi)