For the above example, I'd probably also say that I don't think anyone here is saying that 'all definitions of "Aiki" ought to be accepted.' Rather, I think what many are saying is that interpretations of the term "aiki" may have become different than its original meaning(s) and that these (re)interpretations have become commonly and acceptably used. Language (as I know you know, Chris) is constantly evolving, for better or for worse -- like the word "awful" used to mean something more akin to "awesome" (full of awe).
I think that all that you have said about change and evolving is true. However, I think the stickng point is that many people don't want to be told that they way that they are using the term is different from the way that Ueshiba may have used it.
I understand that, you remember how much resistance Stan got when he started saying that modern Aikido was a product of Kisshomaru and Tohei rather than Morihei. That furor, and the memory of it, has died down quite a bit, and it wasn't fueled by online discussion the way that things are now, but people's reactions were quite similar, IMO.