It would seem that the apparent lack of structure is why it takes so long to learn Aikido...its the bit that makes it somewhat intriguing and unattainable - because it 'works', but it take many people years to figure out why. (Trying to get that 'perfect' ikkyo.)
Personally I believe its much simpler than that.
Understanding the basic structure of Aikido and truly appreciating why its not a 'hard' art, will go a long way in making Aikido less mystified and practical for people.
Tohei, in an interview, said it should not take someone more than 6 months, and that taking years to learn it was just too long.
True, in his time, it was as unstructured - if not more so - then now. Suppose that is one training method...and people obviously choose it and even continue on that style.
Why is this? Out of habit?
What would happen if you just taught things in a structured manner with the basic concepts? Perhaps after 6 months to a year it would not be good for business...and/or you would have to many black belts that would make it look less valuable.
Perhaps we put to much emphasis on aspects of martial arts that are not important. (Not just in Aikido.) - you know, the 'mystical black belt', etc.
So after 6 months and people 'get it' what would that mean for the dojos? Would the instructors be concerned they dont have anything more to instruct? Or that people would still practice but do it on there own?
Dont get me wrong, Im not saying that 6 months is long enough to 'perfect' technique...but if Shodan is where it all 'starts' stateside, from what I understand, then Shodan should be at 6 months to a year and then you can figure out the kinks.
Personally instead of just learning all the movements I try to learn the in-and outs of it as I go. The emphasis is a bit different here, that is why a brown belt can teach here.