Brevity is not orthogonal to clarity; it is clear that overly verbose code is not as readable, just because e.g. it doesn't fit on your screen (or in your head) all at once.
Brevity is a feature of clarity, and clarity usually attends very powerful notions like reuse and application to a new domain.
What's truly orthogonal is some notion of "expressiveness" or "teachability" or otherwise being-able-to-read-and-understand.
The example that you should think of here is mathematics papers. The ideas are stated in their clearest form, which usually is absurdly brief: lemma, theorem, proof. You can then spend about an hour poring over each line to figure out what the heck it's expressing, before suddenly a moment of clarity dawns on you and you see all of the connections together.
Why would they write incomprehensibly? It's not because they don't want to be understood; these are peer-reviewed journals we're talking about here, and someone else must read and OK your work. But it's because when they make the fewest assumptions and the most broad argument, their work maximizes power and usability and robustness.
