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.
I've written a book and explored the landscape for writing another, so let me offer my experience with each of your points (out of order). This is anecdote, so all caveats apply:
# illustrations
My co-author and me were 100% responsible for all illustrations. I've heard tales of publishers dedicating in-house talent to helping with illustrations, but I do not know how widespread this is.
# research
My publisher was not involved in research whatsoever. I'm not even sure how they could have helped had they wanted to.
# design (cover and insides)
My publisher was indeed responsible for this, but it was up to my co-author and me to decide what class of element each section should contain. As far as I understand most publishers have a house style that the authors have very little (if any) say in.
# pr
This is a huge question mark. There were time when I felt like knocking my head against a wall trying to figure the PR strategy (to misuse the term). I expect some publishers are better than others, but from what I can tell the PR for for programming books is limited to: some website, occasional discount codes, a table at a conference here and there and hooking up interviews with authors on certain websites. As far as I can tell, the weight of a publisher's name is valuable as marketing also, but that seems a bit complacent to me. Any other PR strategies that I've missed?
# and all the other bits that go into producing a published book
I don't know what this means, but I suspect it has something to do with distribution channels.
# provide editorial support
THIS. If I ever write another book the availability of quality editorial support is the deciding factor in my preference for choosing a publisher. The editorial process was the most positive experience in the otherwise arduous book writing process. I understand you can hire third-parties but in going with a publisher they have an editorial staff that can rotate if you find your chosen editor unsatisfactory.
I notice you've inverted my order :) I too would put editorial support as top of the list of things a writer would miss nowadays in bypassing a publisher (though of course some books also require a lot of design input). There's an interesting gap there perhaps for publishers to simply supply editorial expertise, or writers to team up with editors and produce books independently - though this tends to result in the formation of a small publishing house, with associated costs.
The other points will vary depending on the publisher and the author of course, and some areas (like design and pr) which might seem unimportant, trivial or simply unnecessary to the author might be vital for a successful book. Re PR for example, this encompasses getting reviews in major trade publications/newspapers, getting radio interviews, getting web coverage etc etc, but that'll vary depending on the subject matter - for some books obviously it'd be minimal, so in your experience it might amount to very little added value. Re research, depending on the topic, sometimes editors will do a lot of the work and pull in writers to write specific parts of a non-fiction book - hard to believe if you're a committed, involved author I know. Re design, depending on the book this might be more or less involved - for some books it'll be a simple template where text takes precedence (fiction, programming), for others each page is unique and the illustrations are as important as the text (a children's maths textbook for example).
Other bits was just a catch-all for all the other admin which goes on in publishing a title - buying the ISBN, typesetting, proofreading etc, along with distribution etc, though frankly I think distribution is the least important part of the puzzle, and for many books there simply won't be a dead tree version soon. I suppose my main point was that publishing encompasses far more than the layperson usually considers, and costs are not solely or even mainly associated with printing hard copy books.
So publishers will change with the coming of the internet, perhaps becoming less important, but I suspect they will always be around.
Editorial support and guidance is traditionally provided by the literary agent, so there is another professional layer between the writer and the market to consider. Big publishers maintain links with literary agencies based on the agencies' reputation for signing and nurturing talent and delivering ready-to-publish manuscripts that will sell. This arrangement persists at least in the world of commercial and literary fiction.
I think that might depend on the territory/genre/author in question - in my experience many publishers provide the sole editorial input, sometimes going as far as deciding on the content themselves, with the author employed to write to hire, but this varies widely depending on the subject matter, the publisher, the popularity of the author, and probably the country as well, and obviously doesn't apply to fiction.
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.