Well you being a versed enthusiast you accept in awarding $30 for the added value, then 15% performance it provides to keep competitive in FPS. You resign to the expenditure to have it, and need performance to run it… as favorable.
To the folks that are just stepping onboard, or never actually played with and without ambient occlusion or PhysX, most won’t hit upon they’re foregoing any enhancement of the actual play/story being presented by the title. Till someone truly experiences for themselves on identical hardware and truly perceives what such sensations of such games offer, it’s hard to quantify. Like between say a 7850 1Gb and a GTX660 with those feature running, they might or might not identify or cherish it as a $30 feature in the few games that take full advantage of it.
An analogy – X brand truck includes water injection and misting in front of the radiator (none do but popular for folk to add it on in aftermarket) for increasing HP and cooling the motor as they pull a hill with a heavy trailer. Is it something every truck owner will necessarily value?