Amazon and other book-sellers are trying to address a number of problems by the use of e-readers.
There is still a stubborn body of customers, however, who want their books in hardcopy.
This entails postal costs which are enormous (to say nothing of the environmental effects). Today’s invention is aimed at lessening these.
Books would simply be printed with a very narrow margin. If you want to study the book and make marginal annotations for posterity, buy the full-page edition. Otherwise, save the planet by ordering a tightly-cropped, tabloid version and avoid shipping a billion tonnes of blank paper.