Agreed. I myself am VERY curious about what Ueshiba himself actually practiced.
I don't think it is that much of a mystery. We have Tomiki, Shioda, and Saito sensei (who are pretty well documented and have published materials available) as well as two illustrated texts (Budo Renshu and Budo) that give a pretty good indication of the content and focus of that era of aikido when Ueshiba oversaw training. Couple that with video and text records of DR's Hiden Mokuroku and a pretty clear picture is possible at least academically.
As for the viability of publishing the Noma photos, I don't think idle curiosity would be enough to make it economically viable.
Out of curiosity I pulled down my copy of Budo
and it has 50+ pages of Noma photos with an average of 5-6 per page. That should be plenty to satisfy the curiosity of most. Moreover it's only $17 new and it can often be found discounted for half that. Really no excuse for not owning a copy.