stating the bleedin obvious
It's been obvious to me for an age that Apple has won the laptop game, never mind tablets.
Glance in any branch of Starbucks (or similar) and check the little illuminated Apple logos. It may be that Apple owners are more likely poseur gits who hang around overpriced caffs, but factoring that in doesn't really explain the scarcity of other brands.
But, given the preponderance of iPhones, once people realise that it's one of the easiest smartphones, it seems kinda logical to scale up to iPad or Macbook.
Perhaps Microsoft's problem is trying a trickle-down from the other direction -- from a 19 inch screen Windows computer to a 4 inch Winphone.