If you target customers who value your product the most and charge a high price, you'll be
making more money per sale but limit the size of your market.
If Amazon were to include magazine subscriptions as part of its ecosystem it would be delivering the content personally and make
more money per sale of each issue or subscription plan.
Sure, writers have control and we
make more money per sale and we need less sales to make more money, but indie publishing is difficult at best and I highly doubt anyone would go into it for security, at least not at this point of the game.
If one publisher insisted on the agency model, selling Stephen King's books for $ 9.99, they would make
more money per sale, but lose more over the long run because another publisher would offer their books under the usual terms, letting the retailer set the price.
The problem with doing this is that — while you make
more money per sale — you're diluting the KU pool, meaning everyone else gets less.