Couldn't agree with you more. I find it almost impossible to buy e-books by going through the Kindle storefront. The lists of books in some categories are dominated by cheap, self-published works with hundreds of glowing reviews. Amazon cheerfully publishes these, of course. Most of them definitely wouldn't make it through a traditional publishing process; the quality isn't there, and they're badly edited.
I find it much more useful to work through the print bookstore instead. What I find there has been through the "middlemen", and as a result is usually of substantially higher quality. Since Amazon lists the various editions of a book, I can flip over to the Kindle version and purchase that, if I want to.
I understand the economics of the situation, and that an author can often earn more money by selling direct. What I'm getting at is that for me, as a reader, I wish Amazon had the ability to simply filter out any content that hasn't been through a publisher. I don't want to see it. I've bought at least ten of them based on the reviews, and haven't read a good one yet.
Of course I'm not saying that good self published works don't exist; they do. Most of them aren't good, though, and they are crowding out works of vastly superior quality. There are parallels to cheap imported goods.
For me, the Kindle store will be useful the day it allows me to filter based on publisher. If you hit the Kindle bookstore as of this writing and select the SF/High Tech category, positions 1 through 9 of the first ten books listed by popularity are self-published. Number 10 is Snow Crash. Sort by average customer review, and all ten top books are self-published.
I guess I could keep hitting "next page" over and over again, trying to wade through piles of chaff.
In short, a publisher's imprint has commercial value, and value to consumers as a mark of quality. I hope they can adapt and not be discarded in the name of middleman elimination.