I think this is a very scary case not because amazon deleted some stuff and why they did it but because they have the technical capability to do so

as this slate article points out the ability to delete things at a distance going to be used by others than just the company, in this case amazon, itself but also by governments and courts forcing companies to get in to their customers machines this way making censorship a whole lot easier

and don’t think that is just rhetoric to scare you it has already happened
FTA:

In 2004, TiVo sued Echostar (which runs Dish Network) for giving its customers DVR set-top boxes that TiVo alleged infringed on its software patents. A federal district judge agreed. As a remedy, the judge didn’t simply force Dish to stop selling new devices containing the infringing software—the judge also ordered Dish to electronically disable the 192,000 devices that it had already installed in people’s homes. (An appeals court later stayed the order; the legal battle is ongoing.) In 2001, a company called Playmedia sued AOL for including a version of the company’s MP3 player in its software. A federal court agreed and ordered AOL to remove Playmedia’s software from its customers’ computers through a “live update.”