Re: Where does "Morote Dori" come from?
Just a thought on my part, and I only have a few years of Aikido exposure, so keep that in mind when reading my stuff, cousins.
Perhaps one reason the morote attack isn't and wasn't taught much is that in executing a technique in response, it's largely redundant; at least in our curriculum, it is quite often.
In Hakkoryu basics we're taught to ignore the second hand and respond as if a single hand is available. Of course, having access to both of the aggressor's hands more than doubles the number of responses available, plus atemi with the free hand is a plus, be it an "eye closer" (目潰) or a hit on meridians before the execution of the response.
Maybe the redundancy is also reason this particular attack isn't a focus in Aikido, just a thought!