vice-versa, most other ereaders DON'T behave the same way; look at some others (try a non-illuminated Kindle). Also, when you're paying a lot of money for screen real estate, YOU should be able to decide what goes on that real estate. Also, actually, most printed books these days have the page numbers in the HEADERS, not the FOOTERS, so if you're going to make an argument that "real books do the exact same thing," it's actually worth looking at a real book before you do so.
The real answer is that none of Kobo, Kindle, or Nook have found a way to deal with the interference patterns caused by the LEDs they use for their backlights at the edge of the screen closest to the location of the LEDs, and so they seek to disguise that location. A solution that did not eat up screen real estate migh be to recess the LEDs further into the bezel, protected behind a clear wall, but no one has implemented that. (Kobo's unique solution is to make the bottom line inverse video, but it is entirely an attempt to mask a flaw in the display technology, and has nothing to do with emulating paper books.)