Dare I suggest that some Aikido teachers who can do 'interesting stuff' learned it by accident after lots of training and have no clue how to teach it in a systematic way becuase they are not exactly sure of what they can do or why it works? Well, it is either that, or for some reason they just point blank refuse to teach what they know.
I think this is very much the way things have turned out. One AikiWeb poster has told to me privately that a couple of the teachers whose aikido I very much admire admitted to him that they didn't really understand how they did what they did.
My teacher has shown us plenty of exercises over the years that he believes will improve our aikido, but I can't help feeling that much of his ability has come from him digesting and redigesting through trial and error what he got from his own teacher many years ago.