Dave de Vos
I would think that a large portion of the "less dedicated aikidoka with many training hours" is still getting something out of training. Why else would they keep showing up?
Habit, perhaps. Like any habit, a training habit can work for good, or it can work for ill.
I think that in aikido, or any martial art, there's also a problem that people can run into as a result of rank testing -- and shodan is probably the biggest danger point. Passing the test becomes the goal, it blocks out other reasons for training. When the test is over, it seems like people look around and find themselves at something of a loss. Not only do they no longer have this tangible goal in front of them, and the specific test criteria, test date, etc. to focus them...but they may find that they no longer have any reason to train. The answer to the question "Why am I training?" changes unexpectedly, and people who get locked into some specific goal and stop really honestly asking themselves that question can end up in the classic and unenviable position of getting what they want, but no longer wanting it once they get it.