I think most of us would prefer to carry as few gadgets around as possible, which is part of the reason why a tablet can seem like such an extraneous purchase. Anything your iPhone can do, your iPad can generally do better and with more comfort, except for one thing… make phone calls. However, iPads are really too big to bake cell phone modems into, which results in consumers carrying around two gadgets with mutually redundant functionality with them, when ideally they would only carry one.
