Carole Baron put up a post at the Huffington Post about why authors still need editors (which, as Gawker points out, really could have used a copy-editor). Baron lists ten (valid) reasons we still need editors and traditional publishing, but I think Scott Sigler gives us an even better reason, through his own foray into self-publishing.
Sigler founded his own imprint to put out his latest book. He says he made ten times the profit per unit, but only sold a tenth of the copies he has sold through a traditional publisher (which, for the not so math inclined, implies he made the same amount both ways). Sigler, an established author, was built up first by himself through his website, where he distributed audiobooks and podcasts, and later by the publishing machine, which put out paper copies of his work, to be a profitable brand of Sigler-ness.
While he points out that his particular self-pubbing method can be profitable, he seems to believe (and rightly so) that it will only really work for established authors who "defect" from traditional publishing--his example being Stephanie Meyer. And yea, she could self-publish and make a ton of money, but a) she was created by the publishing machine, and b) anyone who doesn't have a huge cult following isn't going to do so well.
Sigler says, "[T]hat's the kind of kind of thing that could take away from big publishing and put some of that control back into the hands of authors." What he really means is that control would be in the hands of established authors, who want to take on the responsibility of editing, copy-editing, designing, and producing their own work, but editors and publishing writ large are still necessary for the unknown who wants to be a profitable author. And, perhaps more importantly for this argument for authorial control, if a number of large cash cow authors did defect, publishing houses would lose those profits, and would no longer be able to take risks on new authors, who would be in a worse position than they were originally.
Maybe Meyer could defect, publish her own books, and then start Meyer House. That way, in 50 years we can complain about Meyer House's place in big publishing, quashing the hopes of the masses.