Ninad's analysis of the reasons:
(1) It places China at equal footing with some of the western nations (US, UK & Scandinavian) and Japan, in developing new technology rather than copying it by paying a higher licensing fee.
(2) It lowers the cost of indigenously made Chinese electronics for local consumption and increases the rate of mass market adoption since China controls the standard
(3) Potential revenue opportunity through licensing the standard outside China
Adds WSJ: “China's drive to create new standards in high technology is part of its broader desire to claim equal footing with the world's top economic powers…By creating homegrown technical standards, China is trying to increase the use of Chinese innovations world-wide. And it is using its own large domestic market to help speed up their adoption. By requiring these standards to be used on technical products in China, international companies that want access to that market are forced to make products that use them.”
more great info from emergic. china is one of the most interesting areas to study in technology adoption right now i think