Hm, I've been noisy about this, thanks for your consideration. :)

I have a gut, "social engineer's" feeling that a 'strict' KB has a couple of subtle? advantages:

* Familiarity:  People are familiar with the level of detail and completeness required in [something that aspires to be] formal documentation.  I have a feeling "Answers" and "FAQs" inspire people to be concise, answering the specific question as directly as possible [without writing, for instance, an "Other Considerations" section] and moving on.

* Completeness:  Per the above, a good KB entry will pull all relevant information into the KB, inspire people to reinterpret documentation (or discover/acknowledge gaps in documentation), and reduce the number of documents/tabs/... a human has to peruse to "get a grip" on some particular topic, be it general ("Frequently Asked?") or specific.

* Collaboration:  Looking at an entry created in the Launchpad FAQ system -- I picked https://answers.launchpad.net/soyuz/+faq/167 -- it appears the system is one-way; when someone [limited to people registered as an Answer contact?] finds a good answer, they can nominate it up to being a FAQ, but there is no in-band [on the page] mechanism for other people to improve on that answer; out-of-band I assume they can jump into the original Answers thread or chase down the author.  The model I'm proposing, basically a wiki with blessed checkpoints, makes it easier for more people to pile on and potentially improve the entry.

* Accessibility:  In the 'social' sense, related to collaboration and familiarity -- as simply a Person Using Ubuntu (and other Launchpad projects) at the moment, I know I'm hesitant to start smashing links in Launchpad unless I really feel strongly about accomplishing something; who knows what kind of "noise" certain actions will make?  Will I end up bothering or wasting the time of people in more active roles (and so making a negative contribution on the whole)?  I haven't checked myself with a stopwatch, but it feels like there is maybe a two or three minute window per-page-view to get a casual Launchpad visitor who just showed up to check a bug or try to solve a problem -- as opposed to a "developer" working in the system every day -- to decide to drop everything and "participate."  From my perspective, the 'Nominate for FAQ' link (and much else on Launchpad!) has a "Someone Else's Problem" field around it unless I'm deeply involved and absolutely convinced something deserves to be in someone's FAQ, while I know [in general web-browsing experience] that I'll quite often end up making a wiki edit or writing a comment because those are familiar actions with familiar and understandable side-effects that can grab me within that 2 or 3 minute page-view window.  Once that hurdle's leapt, most people think nothing of spending 30 minutes or more trying to help out with a comment or edit itself.

The FAQ system does look good for what it is, and a good start on an approach to the overall documentation question.  But even "infrequently-asked" questions deserve good writeups and community editing if the people infrequently asking them care enough to dedicate their time.  [Of course, sometimes stumbling into a piece of information like that is how you discover a great new feature or 'trick' to using your software in ways you never knew you could!]

I'm not sure if anyone's doing person-off-the-street testing for Launchpad, and there'd be translation issues outside English, but it would be a funny experiment to take the existing Answers feature, rename it "Knowledge Base," and see if people interact with it differently just based on the name.  [Similarly, if 'Nominate as FAQ' became 'Nominate as Important' or 'Nominate as Interesting,' what sort of results do you get?  But I do agree that you can spend lifetimes on this sort of scientific inquiry, which is why the Mac didn't ship until Mr. Raskin was nudged off the team and Jobs told them to take what they had and put it in his pretty case. ;)]