Re: Origin of ushiro ryote and ryokata dori
I am just pointing out that Daito Ryu has ushiro kata where first nage turns around, and then uke comes in directly form the back and attacks in some manner. They are similar to kata that exist in various other jujustu-based koryu schools.
Seems like a good answer to the question of where the Aikido techniques come from.
And as to why Aikido doesn't practice the way Daito Ryu does, my answer is because Ueshiba was never interested in passing on kata to his students which they could work on. He just did stuff in front of them, with context removed.