I odont know about the pants pocket thing, is something you said!, I' dont think that would be something people wants either...
but having a device that size that is half size when folded, is something very useful, first, the screen is not exposed when carrying it around, the smaller size (not volume...) would make it fit better in smaller bags, a laptop bag is something maybe you are used to, but not me, and not many people I know that travel with the laptop w/o case straight into the luggage. You can do this with regular iPad, but the screen would be much more exposed to cracks.
why laptops fold??