It is a proven fact that spring hinges are likely to increase the durability of a frame considerably - by as much as 80%. Within that context,
Where did you get that fact? An actual fact is that frames that have/had spring hinges for Oakley such as A wire 2.0, C wire, and E wire 2.0 and 2.1, (and their TI counter parts) did not sell as well as the frames with out spring hinges. (the exception being SQ wire 2.0 and Big SQ wire, which is why the new SQ as well as their TI counter part have them)
I see this as more of a measure to create glasses that have less durability and therefore wear out more quickly... and consumers would then purchase more glasses (as replacements).
Your kidding right, having a spring hinge means more moving parts, more moving parts mean more to break. I have seen more problems from sunglasses with spring hinges than those without.