If I could have stated things as well as Mr. Gano did,I would have. Not having the gift of gab, I would like to point to Mr. Gano explanation. The way he put things is way better than how I put it. Please don't confuse Mr. Gano for me, even if point to his explanation. It would not be fair to him.
As I respect your comment, please feel assured I am responding in the context of the original question. Yes, the Founder had teaching skill, otherwise Aikido would have died shortly after it's birth. No, I don't believe he held anything back from his students. Despite the arguments his students never came close in reaching the same level of proficiency as he did. I am not judging the Founder on the opinions of his students abilities. If anyone is to judge his students abilities it would be the Founder.
I would like to close with this thought. Today, Aikido an international organization existing for decades with hundreds of thousand students who have passed through its door and thousands more passing through right now. The future is still bright for Aikido, I don't see this star dying soon.
I cannot clearly gauge how you would like us to evaluate O'Sensei's teaching abilities. I do not think that he ever tried to hold things back. I do think that he was hemmed in by his unique personality and by the teaching modalities that he was exposed to and utilized. I also believe that there was a genuine disconnect between his expressing his thoughts, based upon a formal education in Chinese classics, and his students who were taught in a more western-based system. O'Sensei talked about things in a manner that reflected knowledge of Chinese classics to people who did not really understand what he was saying because they did not have that background of understanding.
The larger issue of the state of Aikido today is one that I look at differently. Just because it is popular, does not mean that a high level of learning is taking place. Martial arts is really based on a teaching modality of long-term, personal exposure and training with a highly skilled teacher, compounded with a lot of personal training. This teaching paradigm does not translate well into a setting where there is one teacher and many students. I look at our population from the statistical percentage of the bell-shaped curve. A lot of mediocrity, few incompetents and few highly skilled. Our art will continue into the future like a lot of other martial arts.... mostly watered down with a few highly competent people.