So, to clarify and be able to indicate support:
It seems to me that there ought to be a way (there should be a way; it would be a good feature to add to have a way) for moderators to "de-community wiki" under certain circumstances (maybe a quorum of moderators might be required, much like a quorum of users is required to close down a question?). Two such circumstances might be:
A post that is automatically community-wikified due to multiple editing; especially if the history reflects that this was not done to "game the system", and was done in a relatively short period of time; e.g., my long post described above hit 8 edits just by me trying to tidy it up and clarify things, even before I made the big rewrite that put it over the top.
A post that gets community-wikified prematurely by a moderator who later changes his or her mind.
Again, I can understand that the "no recovering from community-wiki" has a reason to be; but perhaps requiring several moderators to agree to recover it might be a way to keep a door open slightly ajar without opening it up to wholesale abuse.
Added. I guess my main proposal is this: give moderators an opportunity to exercise some judgement. I would suggest implementing the ability to de-community-wikify a post during some specified short window after it becomes a community-wiki (a few hours, a day, something appropriate), along the following lines: author must actively request and justify the request (through a flag-like request, or a flag itself, perhaps) and one/two/three/an appropriate number of moderators would have to acquiesce to the request (much like we need multiple non-moderators voting to close a question before it is closed). I don't really care much what would then happen to reputation for up-votes received in the interim (between it becoming a CW and it being de-CW-ified through this process).