Because people may only want to carry a single device instead of two. Obviously with the poor battery life and weight the Pro doesn't quite get there, but it's

Because people may only want to carry a single device instead of two. Obviously with the poor battery life and weight the Pro doesn't quite get there, but it's clear this is the evolutionary path Microsoft is headed for. Things should get really interesting with each iteration of the device. For now, the device will be considered a flop though.