The amount of usage they're talking about is road warrior-ish. I'm sure many people buy Iphones just because they like the way it works. But the amount of activity these studies are talking about - these Iphone users are using them in place of computers, probably in the car, on a plane, at a restaurant, in a meeting, and so on - places where it might be inconvenient to whip out a laptop computer.
I have an iPad and an iPhone, and what you just described is what I whip out the iPad for (along with the iPhone too), and doing so as a grandpa (as other grandpas and grandmas that I know do too) ... and NOT as a road warrior, but in the course of my very ordinary life about town ... :-) ...
Now a number of years back, I was more of a road warrior (but before the iPhone), and I used my IBook, along with a stand-alone GPS that tied into my iBook with Bluetooth, and I tied into a mapping program ... so used the iBook and GPS (and other programs on the iBook) in the same way as the iPhone and iPad (now), except that I’m not in the road warrior mode as before ... and neither are the other grandmas and grandpas that I know ... :-) ...