I've sent many suggestions to the Kindle people of things they could improve on the Kindle, all of which were very simple to do. The years go by, they've done exactly 0 of them.

One of them, for example, was an option to eliminate the margin in a pdf display. The pdf already has a margin, so there's the pdf margin plus the margin the ereader puts around the pdf. This significantly reduces the number of pixels displaying information.