For sunglasses, plastic is adequate, metal is adequate for the task. There is no higher standard, even Oakley on its website rates the two frames as equivalent (alloy and carbon). Cutting the fibers, although offensive from a purist isotropic standpoint, does not cause the product to fall below the strength needed. Machining for 24 hours, however, excessive, 4000 dollars excessive.
Compression molding of random carbon fiber chop would accomplish the same thing, and have near zero waste, a similar cosmetic fiber finish. Google the Audmars Piquet Carbon fiber watch for some jpegs of this process of near net shape manufacture.

Of course the Oakley design is just an over the top celebration of excess in manufacturing in the same way that the swoops and curves of the aesthetic design are needless and excessive.

I am guessing though that Oakley could not get defense company to make the carbon fiber for them? Imagine the adverts from Oakley touting the connection between badass stealth carbon fiber helicopters and their badass Blackwater employee sunglasses.