This all mystifies me. You know what else has edges that go yellow like that? Paper books more than a decade or so old.
Honestly, they could have sold this as a
feature ("looks even more like paper!"). Maybe the next edition will have algorithmically generated splotches and weird faint black bars from the printing process, etc (algorithmically generated because they must always be rendered at the same places on a given page, it wouldn't do for them to be random). Next up, iffy font rendering on the odd page... next up after that, a .1% probability of misordered pages or big 16-page missing chunks because of missing signatures and printing problems
"Kindle: now
just like paper books!"