Apple has always defended its size 10 ", suitable for single shelf, which is loved mostly by Steve Jobs. But now, the market pressures eventually convince Cupertino to work on a smaller model.
Apple never chose his screen sizes randomly. In digging into history, old-timers will remember as the output of the Mac IIsi with its screen in "portrait" which surprised everyone (but very convenient way to view an A4 sheet on the screen). At its output, the 1.0 iMac was also equipped with a 15 "screen (not 17, yet became the norm), the iPhone is stuck 5 years with its 3.5" ... Almost every time, Steve Jobs came to defend their choices, dictated by him, by compromise and ergonomic techniques. Thus, with its 10-inch diagonal, the iPad was as iPapy-format ideal for use that flowed for reading magazines, surfing the net, watching videos proves that Jobs was not wrong.
The format of 8 "was defended tooth and nail by Apple during the presentation of the iPad mini displays as 35% additional area in 4/3 compared with tablets 7", often 7/9. iPad mini was born of this approach: the market was the applicant, the competition was organized, but it was perfect the concept in finding acceptable compromises and more importantly, without losing an entire application ecosystem.