It's a straightforward attempt to use its position in the marketplace to squeeze everybody else. Because it's a virtual retailer, it probably won't work (setting up in competition is so easy).
Amazon is not entitled to do it, just because it thinks it can.
When the courts have finished with this, perhaps even traditional publishers will understand. You can't use a monopoly position unfairly.
If Amazon IS allowed to squeeze small publishers, then it will squeeze larger ones. Just like the High Street retailers used to do, before the internet began to sideline them.
"...the likes of NickP can rant on if they like"