Aikido is about joining and blending and avoiding. It is about whatever it takes to deal with the given circumstances. Trying to put it in a box to meet a certain teacher's criteria doesn't make any sense to me. How can there be a separation of aikido and movement? Any feeling that can done standing can be maintained in movement as you blend and redirect or enter with uke.
Sure, but the problem with moving (and this is why O-Sensei didn't teach Ki-no-nagare until San Dan) is that there's so much more stuff happening, so many more variables to account for.
Children learn to stand up before they walk, before they run, for the very same reasons - it takes their physical systems some amount of time to learn to cope with the increased variable load.
One of the biggest problems in Aikido, IMO, is that people start moving around too soon and can't feel that everything that should have going inside their bodies is actually falling apart.