There is no such market segmentation or opportunity to capture the consumer surplus with e-books, so potentially that money is just lost. Does greater volume of sales make up for that? Who knows, Amazon hasn't provided enough data. On the plus side, Amazon is incented to maximize their own revenue and since authors get a percentage of the book sales revenue in theory that means Amazon should be incented to maximize author revenue as well. Though, as always, it's not quite so simple.
What? If anything, it's MUCH easier to do so with e-books, with elastic pricing. Maybe it's not Amazon's current proposal, but I disagree with that part of your argument.
You do make a good point about consumer surplus.
Edit: I'm pretty sure e-book publishers can get creative ways to add to consumer surplus (be among the first 100 to buy the "premium" edition and get a character named after you in the sequel!), maybe something like kickstarter's model.
As for alternate e-book models, as you point out, there are many. And actually crowd funding is a major way to capture that latent consumer surplus (which is one of the big reasons behind its success), but even that is not necessarily a panacea.