I could be wrong, but isn't structure a necessity?
because without structure, the body would just be a noodle. So we have to have some way to hold the body together (structure) in order to direct force to and from the ground. Am I incorrect in this assumption?
Given that you have some experience with chinese martial arts, I was assuming you were referring to the concept of structure as typically expressed in chinese martial arts. That is using certain alignment of the bones to transmit power. If you were referring to something else, please let me know.
Now since I can't post that video I earlier referred to, I will describe what happens. The guy giving the seminar has someone pushing on him in a position where his bones are in alignment where he can use structure. He then moves into a very compromised position where he is leaning over sideways with a bent spine (it looks like his body is making a C with his hips stuck way out to the side bent at the side instead of forwards) where he can't use that structural alignment to convey his opponents push into the ground. The pusher still can't effect him. If someone who doesn't understand jin, copies this shape, they tend to fall over when pushed.
This point of this is to show that the concept of jin (more specifically peng jin, as one's own body weight reflected off the ground) does not rely on structure. If one argues that you need second person for aiki, then jin isn't aiki, but to answer my earlier question, I guess it would be come aiki once you have a second person committing their weight/effort onto you.
So you can still convey weight into the ground and back into the opponent through connective tissue, tendons, joints etc, as well as through fascia, but you still need to commit this weight straight into the ground even when bent over. This is where Mike Sigman's suit model or discussion of the balloon man comes in. Sure, you can tense muscles to convey power too, but most people knows what happens, the body becomes stiff and you get taken advantage of.
Structure is great, and relatively easy to learn, but I'm not sure if it is really aiki or not, but it certainly can be used to convey forces very well.