Selling ebooks is just not that complicated; it's an open question what value amazon brings to the market (in that sense, it's the exact same problem as Spotify.) If the top publishers jumped ship and started selling ebooks directly, I'd follow. The vast majority of the self-published stuff on amazon is utter shit, demonstrating both the value of a publisher as a filter and the value of editors. Obviously there are gems, but the majority is awful. Also, to be blunt: if you think that, were amazon to put the publishers out of business and therefore gain direct publishing control over most ebooks, they wouldn't take a hatchet to writers' pay, you're incredibly stupid.

Thinking that (1) writers wanting people to have more access to literature, and (2) working in their self-interest to be paid are incompatible is silly. Unless you're voluntarily giving up your salary so that more people can have access to software (or whatever else it is you do).