It's really a simple question:
What is most important?
1. Good documentation, or
2. freely editable documentation?
I do think that it is possible to have good documentation even if it is not
freely editable. Contributions can be made in more ways than wikifying
the content. And if the content is wikified and contributing is only
possible through registration, only those that are motivated enough
goes through the process of being authenticated.
Also, all the worlds problems cannot be solved with a wiki. There are countless
examples where a wiki is not the answer, and there are countless examples
where a wiki is the only answer.
When you have a hammer, everything is a nail.
For contemplation:
http://www.bbspot.com/News/2003/09/net_well.html
Regards,
Mathias