Ukemi is bad for your body. Period. Learning it is smart, continuing to taka falls your whole life is not good for your body. It will not teach your aiki. It will not teach you internal power, you do not need to fall down to "feel your teacher" and learn the waza.
You can learn power and aiki and how to use it, without falling down at all. And in the process some of the damage will be reversed through training the body correctly.
I continue to prove all of the above, (and not just talk about it) ...month after month as I meet so many of the damaged teachers and players.
Well, the very nature of the question defines the lack of understanding of what it is we do. Taking lateral loads is nursury school and just one of many benefits of proper training. It is far deeper than that and broaches the topic of the connection between internal strength....and Aiki.
Interesting. I note that no one has really discussed 'what is elbow power' in this thread.
As a historical tidbit, there is a concept of "hiji no ri" or "elbow power" (perhaps more accurately, 'the principle of the elbow') in Judo. An aquientance of mine (who's trained with both Sam Chin and Akuzawa, as well as being Dan ranked in Tomiki aikido) has mentioned that 'elbow management' is a hot topic in those arts. Considering something like Wing Chun (which seems to have a very interesting way of using the elbows / arms), I think something like this might be a fruitful discussion.
In regards to Ukemi; it's my understanding that certain hard chi-gung exercises involve hitting oneself (lightly!) in order to 'spread the chi'. Actually, if you think about it, something like a side-break fall could serve a similar body conditioning purpose. I also realize that Kuroda has an interesting article on the use of ukemi (or rather, ukimi) and how it relates to his internal training.
In other words, ukemi training (as it is, without turning into bogyo) might serve a good purpose