Again, that's why I thought he was teaching them outside of normal classes in a sort of kenkyukai format. This format continues in most Ki Society dojos that I've visited, separate Ki classes and Aikido classes.
My understanding is that the formal division of Tohei's blocks of instruction into "aikido" and "ki development" began when he was Aikikai Hombu Chief Instructor.
If I have this right, a number of Hombu Instructors were concerned that the classes he was teaching (particularly at locations outside the Aikikai) fostered a misimpression of what "aikido training" entailed, precisely because of his emphasis on these exercises.
Packaging them as a discrete block of "ki development training" was (initially at any rate) a way of making the objections moot, because it enabled him to say something to the effect of: "No, how could these classes give anyone a misimpression of what aikido training is when I call them "ki development," teach them as "ki development," and don't call them "aikido?"
Why the exercises were retained and delivered in the particular format used in Ki no Kenkyukai is obviously a much broader question.