What's smart and not is relative to each user, for whatever task they're doing and their use case. Just because it's "not smart" for you specifically doesn't make it not smart for everyone else.
Some people might want the latest processor and a thinner form factor, in which case the MBA is perfect for this, and buying a refurb is "not smart."
Why is buying refurbed not smart? It carries the same warranty and standards as a new macbook. Besides a macbook air is supposed to be cheaper than a full fledged mac.