FWIW I just reread Ki in Daily Life. Sometimes it seems a bit dogmatic and oversimplified, but I was also struck with the realization of how much has always been there. The breathing exercises are certainly interesting to reread given discussions I've seen over the last few years about breathing, tension, winding, etc.
Our Kanshu has asked that we spend more time on some of the old ki tests and training as it was felt that we weren't cultivating those skills enough in the students. Some instructors I know go back long enough to remember training directly with Tohei et al. For me, I've been re-reading a lot of those old books, revisiting old notes, and it has been good, for me at least. Through new eyes I see a lot of what had always been there, lurking under the surface. Just with new abilities now to understand, explain, and hopefully get better at them and pass them along.
Another observation... In most areas of non-trivial difficulty there will always be a very large number of people who never really "get it". Of course they enjoy their practice and get any number of benefits from it. But the group of those who get *really, really good* is often a very small number. It is true of martial arts, sports, heck, pretty much anything. Those who are *truly* looking *and able* to get good will make the effort to get out there and find it, whatever *it* turns out to be. But ya gotta have both. That there are a lot of people training and teaching who aren't at the very highest levels shouldn't be surprising given the incredible popularity of the endeavor. Welcome to the greatest strength and paradoxically the greatest weakness of Aikido. The "grading curve" doesn't change. For every 100 gravitating around the mean performers there are only 1 or 2 really top notch performers. If we go to 200 then we're talking about 2-4 top notch people.
Lots of people play tennis. Few can hang with someone like Federer. That doesn't mean those who can't shouldn't play. Nor should we lament the sheer number of people who can't hold their own with the world class players. We should, however, be aware that most of us cannot hold our own. That, I think, is the real issue -- the self-delusion that we're all really good at it.