It's not about the writers, it's about the system, man!
Self-publishing is no different than a band playing shows and selling its CD or someone putting together an indie movie and trying to find a distributor. 90% of those bands stink on ice, 90% of those movies are hideous, 90% of those self-published books aren't worth the bytes they're made of.
But that final 10%? That's Fugazi. That's the Blair Witch Project. That's the next Michael Chabon.
The difference between film, music and books aren't the quality of what's being produced, but the means of distribution.
I worked as a writer covering the film industry for years and years (I still do, from time to time) and trust me: for every movie you see in theaters, there are 500 you don't. And for every movie that gets any release whatsoever (DTV, VOD, festival screening only) there are 100 that don't even make it that far. There are hard drives and storage vaults across this country full of movies that ran out of money before their final sound mix or color correction could be completed and have been seized by the lab. I run a film festival and go to a lot of the major markets and you'd be astounded to see how many, and how bad, the selection is out there.
Same with bands. Pick up an NYC paper. There are a few hundred performers putting on shows almost every Saturday night in the city, from jazz vocalists, to queercore bands, to DJ's, to classical quintets. And almost every single one of them will be selling a CD at their show. But the distribution channels of music, more than in any other art form, are divided so cleverly that if you're an early music fan you will never run across tracks from the biggest New Jersey punk outfit, but you will have access to almost every early music group of any value (and many of none) from around the world.
The problem with books is that it's still the Wild West. There is all kinds of access, so many channels for distribution, but not enough curation. Right now, the curators/gatekeepers are a tiny little band of well-paid publishers with high overhead who have done a lousy job of keeping up with technology.
The bigger question is who's out there in the Wild West curating the selfpublished stuff? Who's reliably calling attention to the wheat and pointing out that it's different from the chaff? Who is building a reputation as a critic or a curator with taste that can be trusted?