Here's an interview with Sarah MacLachlan, president of Canadian publisher House of Anansi, that mentions self-publishing. Quotes and my thoughts:
I think publishers have a place as cultural aggregators. We put a stamp of approval on something by accepting it and by saying, "Yes we want to get behind this and put our resources behind it." That's something that a lot of people don't necessarily think about. Publishers add value.
Maybe, maybe not. Depends on the publisher, I guess. I will admit that most readers tend to assume that anything from one of the major publishers meets a certain minimum standard of quality, whereas indie publishing can be all over the map.
The other part is collection. Amazon is saying they're going to give you 70 per cent, but what happens on the day when Amazon decides not to pay you or takes two years to pay you? You're still a lone ranger out there trying to get your money back from them.
Personally, I'm a lot more worried about getting my money from a small or medium-sized press than from Amazon. But seriously, this is a concern for any writer dealing with any publisher. Suggesting that Amazon is somehow less likely to pay seems a bit disingenuous to me. And if Amazon does screw me over for some reason, at least I can quickly and easily pull my books, which is very unlike getting out of a contract with a traditional publisher.
I think anybody who wants to publish a book ultimately wants to have it published by somebody. In some way that gives them a sense of value, in saying "I wrote something that was good enough to be published by this company."
Personally, what I want when publishing a book is to make money and to reach readers. That's where the real sense of value comes from, for me. Others may feel differently.