This is a weirdly aggressive take without considering variables. Almost petulant seeming.

6” readers are relatively cheap no matter the brand, but cost goes up with size. $250 to $300 is what a 7.8” or 8” reader costs, but there’s not a single one I know of at 6” at that price.

There’s 10” and 13” models. Are you saying they should cost the same as a Kindle?

Not to mention, regarding Kindle, Amazon spent years building the brand but selling either at cost or possibly even taking a loss on the devices as they make money on the book sales. Companies who can’t do that tend to charge more.

Lastly, it’s not “feature creep” to improve the devices over time, many changes are quality of life. Larger displays for those that want them. Frontlit displays, and later the addition of warm lighting. Displays essentially doubled their resolution allowing for crisper fonts and custom fonts to render well. Higher contrast displays with darker blacks for text. More recently color displays as an option.

This is all progress, but it’s not free. Also, inflation is a thing and generally happens at a rate of 2% to 3% annually or thereabouts during “normal” times, and we’ve hardly been living in normal times over the last decade and a half.