Well, the iPad never pretended to be a full mobile solution (i.e., it is mainly a media consumption device). The problem I see with the MBA is that it has been minimized beyond a realistic point (i.e., just ONE USB port, no FireWire ports and no built-in optical disk drive). It is marketed as "more" mobile. The reality, however, is that if you want to do any of the things you EXPECT a computer to do, you have to carry enough extra accessories (i.e., MBA SuperDrive, USB Hub and AC Adapter, etc) around that any advantage in mobility you might have gotten from the design no longer is an advantage because you have to remember to carry extra things around just to get a minimal level of functionality out of the computer. My biggest complaint with Steve is with his willingness to minimize a design for the sake of minimizing it, sometimes discarding consideration for what is a practical minimum (for instance, you could get away with two USB ports as are on the MPB 13"/15"; however, ideally, it should have at least three regular USB ports or two regular USB ports on one side and a mini USB port on the other side).
That said, this shortcoming would be less significant if the next MBA had a single LightPeak port that you could concurrently run several different peripheral protocols over. We don't have that yet and so I say that this design is ahead of its time; but, then again, Steve always has been.