It's providing high capacity devices to those that need them. Someone who has to carry a lot of documentation around with them for example. I can see pilots and sailors making use of the extra capacity in time. But the other reason is Apple make a lot more profit on an iPad than they do a Mac Book and the high cap storage devices are a lot more profitable than the lower cap units. Offering a 128GB device just makes good business sense. Some people will want it, and a few of those will need it. Apple doesn't care if you need or want it - they make a big profit from any sale no matter what.