As Ellis Amdur notes, some folks (like me) are doing aikido with some infirmities and sharing what we can do with others who have infirmities, and I believe that is a good thing - but I have never led such a class for a single evening without being mindful of embodying to the best of my abilities, and sharing the key points as best I understand them, about the martial applications or principles our training is based on and pointing out some practical application of what we are doing.
When a student asks me a pointed question about why, from a practical defensive perspective, something is done this way rather than that way, if I can't demo it on the spot, we play with it for a while until it makes sense.
Otherwise, WTF are we doing while we work on posture, connection, kata, etc?!
Ah, there is the question, why are we doing this anyway....I am sure there are as many answers as there are practitioners.
Aikido as a self-defense is so much more than who wins the fight. It is about becoming the best person one can become and then bringing that best out into the world to help transform the world inch by inch...circumstance by circumstance.
The irony of being able to really defend oneself is that by going to the dark place and facing it, one may never need go back there.