While it's only 2% of the revenue of the i-Device, it pays over 1 MILLION people a living, middle class wage in China. Foxconn (i-Device maker) employs over 920k directly (wikipedia). They also get components which are also China made, not to mention how the wages stimulate local economies. Foxconn has supply chain requirements which effectively requires payment of living wages. Without i-Device, several million jobs would be lost.
This also doesn't factor in how China forces Foxconn to effectively bring prosperity to poorer parts of China. There are many parts of China where people are under-employed and Chinese govt effectively dictated to Foxconn to create factories to train worker, to bring wealth to stimulate local economy (building factories, employing people, etc) and every few years kicking them further inward while the local govt run factories take over the trained employees to make mature products and fulfill internal demand
China is all about the 8% growth, without i-Device, and foreign input, it simply would not be possible. The local corruption is too inefficient to maintain the growth.