I think it is interesting that many of our aikido leaders who are expanding their training are moving outside aikido to do so - Dan hit the nail on the head. Current aikido curriculum is incomplete education. Leading instructors have tried different (personalized) approaches to adjusting curriculum to solicit a more successful result to a greater or lesser extent.
I think sometimes we forget that many of the earlier Ueshiba students (pre-war) came to aikido with a pre-education in martial arts. The experiences under which aikido was "created" were related to a collection of martial experience (although arguably Daito Ryu was most influential). It should not be surprising to find that experience outside aikido may significantly improve training and wisdom to better transmit aikido. I think the quiet move of key aikido people to begin seeking information from other martial arts is indicative of the potential...
Obviously, the other factor that contributes to this observation is the duration in which the curriculum is taught. It should reason that the length of practice also improves training and wisdom. Martial arts are reduced to hobbies, to which we neither devote significant time, nor effort. I think the comment begs the question, but arguably most people do not express a need for fighting knowledge that would make significant time investment in training worthwhile. Most instructors could not impart onto a student fighting education giving the time we commit to training - it is an unrealistic expectation.
Who realistically expects modern aikido to produce another Tohei sensei? O'Sensei? Saito Sensei? Saotome Sensei?