Publishers at the moment are a necessary evil. Traditionally they publish your work, handle the distribution and all the stuff that's basically not the writer sitting their ass down and writing.You've missed a few vital parts of the publishers' role here with your handwave about 'all the stuff that's basically not...writing':
Publishers (the good ones at least) provide editorial support, illustrations, research, design (cover and insides), pr and all the other bits that go into producing a published book (ebook or printed, there isn't actually a huge difference in effort). A book without this is often not a very satisfactory affair. Much as music publishers provide an umbrella under which various services like recording, mixing, production, pr etc are provided which are essential for most musicians to produce their work.
A book at manuscript stage is often inchoate and rough at the edges, and the role of the editor can be critical in suggesting changes or cuts and guiding the author. This is esp. true of non-fiction, but also true of fiction. Just like shopkeepers, publishers are a profession which will probably always exist, as there is a gap between the raw materials and what the public likes to consume, they're not a necessary evil, they're just an intermediary, which is sometimes a useful thing to have.
The publishers have of course taken advantage of the dominance they have over these services to try to wring every last bit of profit out of writers and leave them with the minimum of money for their efforts, and a correction is IMHO due, but there may always be publishers who seek to promote, nurture and improve writers, just as there will probably always be musical publishers/patrons who pay for the ancillary services up-front which musicians can't afford/are not skilled in, but which are essential for producing quality music. That doesn't mean musicians or writers should not have more control and be more fairly recompensed, but there is more to writing and music than is dreamt of in your philosophy.
Before publishing we had the system of patronage, which served a similar function for artists/writers/thinkers but introduced other distortions (influencing what could and could not be written for example), I'm not convinced that was better, but the current system will certainly be disrupted by the web as Atwood implies.