From what I understand, a big part of the appeal of the MBA is that it's light and thin enough that you can basically forget that you've got it in your bag. For people who travel a lot, that's a big deal. For some users, then, the laptop's physical attributes (dimensions, etc.) are important aspects of the machine's overall usability.
you can basically forget that you've got it in your bag
Except you can't, because you're worried about crushing it, due to a relatively frail case, or you're worried about scratching it because it looks pretty.
This is why I ditched an MBA and carry around a netbook.
One of my clients is swapping all of their sales people out of their windows laptops and into MacBook Airs because the sales people just need office and a web browser and the airs are far more impressive looking.
I have another client where the sales people have windows laptops, but they're not allowed to bring them to client meetings, instead they have to bring their iPads.
Well, that will depend on the user. In my case, I carry my laptop for probably an hour at most (round trip) and then set it down and use it for 2-3 hours at least.
A lot of people hated the most toilet-like car I can think of, the 1998 Fiat Multipla. It still sold a whole lot, and I personally liked it. Making design pronouncements is a tricky business.
