The reason documentation sucks in Linux is because programmers are writing it. It's not because of the myth that programmers can't write, it's because writing is not really their passion-- creating the programs is. I mean, give me a choice between fixing/improving my code and documenting it, and the choice is pretty damn obvious.
One thing I learned in my tech writing days-- programming ALWAYS outpaces code. ALWAYS. A business can keep that in check (or not, which is frequently and increasingly the case), but in FOSS the programmers are just going to run away with their passions (and rightfully so) while the documentation lags. Someone might try to write some documentation for software they love after the fact, but the FOSS release cycle is such that the documentation will be outdated before it's completed. Very unsatisfying.
Bad documentation is the price we pay for FOSS. Generally, I think FOSS is worth it.
If I had money lying around, I'd try to setup a clearinghouse for web boards dedicated to answering questions as they come up, and create the best damn search interface I could. In short, a better system of what we kinda of have now.