One reason for the popularity of these devices is that people are producing more content. Folks aren't watching CNN/BBC on an iPad but self produced Youtube videos and they're reading more than NY times bestsellers on a Kindle.

There is an assumption here that people with a PC will automatically become producers which I think is wrong. For people to become producers they need incentive and opportunity. These devices and the ease of content creation is means the opportunity bar is much lower (e.g. you don't need to get a publisher to agree on a manuscript to publish); and the incentive is higher (you can monetize content you produce whether its apps, books or videos much more easily).