The following article about the MacBook Air proves that Apple cares about how it's laptops are manufactured. Though the article looks down upon the effective wastage in the manufacturing process, I think the design decisions might have come, so as to not make any compromises in the long term durability. They do market it as an extremely portable laptop. I wonder which advice would Apple choose, feedback from manufacturing on how to cut costs or design decisions made by it's team to make it a highly durable.
Though without knowing what really went on, this is pure speculation on my part. For all you know they did not have time to rework the design to save manufacturing cost!
No Waste Outside, Nothing but Waste Inside
Some of quotes:
"What astonished all those engineers was the fact that the computer had a very costly structure. For example, it used an extremely large number of screws to attach components. About 30 screws were used to attach the keyboard alone."
"The MacBook Air gives me an impression that its manufacturing plant packaged the computer exactly as ordered by Apple."