The fact is that the pareto principle is alive and well in aikido as it is in anything else. 80% of the people are there for reasons other than what the serious 20% are their for. Out of that 20% ....probably less actually will figure out a few other things.
Our culture is different than Japan when Aikido was started. Thus, the point of entry into the arts must also be very different. I can only imagine since I have never been to Japanese or experienced it pre and post war in Japan.
So, I think we bring people in however we get them in, and alot of them will leave, some will stay and dabble, fewer are willing to put in the time to really develop skill.
Just to throw in my two-cents worth, I think the real mistake is in trying to package the "internal" skills (I'd debate what that means, FWIW) as a martial phenomenon. I don't think these skills were martial to start with (another good discussion) and I'd note that both Ueshiba and Shioda indicated that these skills were more or less an investment for old age. I agree with that idea. Are they martially important? Sure. But they're much more important for daily life and usage... uh oh.... Tohei beat me to the punch on that one, didn't he?
As I see it, the baselines skills of the ki/kokyu things are fine in a dojo atmosphere, but some way has to be found to teach/convey them as daily movement, etc., skills. Will you get more powerful doing difficult standing/moving exercises? Sure. But the baseline skills can be (IMO) taught more easily than that. Once someone understands the baseline skill-parameters, then they should be able to invest as much time as they want in order to become as powerful as they want.
Certainly we're quite different from the earlier, more martially-oriented cultures. My comment is that everyone in Aikido (and other arts) has seen how easy it is to lose these skills in general, so it's worthwhile to find an accomodating level as a baseline and quit worrying so much about martial effectiveness. Martial effectiveness is good, but general usage should be more of a consideration, IMO. Oh... and I don't mean having babies with it.