The Wikipedia article about the hangul script points out that people who were literate in Chinese characters resisted a simpler writing system that would broaden literacy, and thus threaten their social position. The same happened in Japan (where kana syllabaries were derided as fit only for women) and in China (where a brief period of using Chinese characters for sound only, rather like Japanese kana, occurred at the beginning of the Han dynasty, but was suppressed by scholars). The Chinese case of early sound writing was only recently rediscovered by history, as archeology in sites from that period showed how many writings there were that used Chinese characters strictly for sound value, in violation of etymology. Chinese development might have been very different if broad literacy had occurred two millennia earlier.
Thanks for pointing out the early Chinese phonetic effort, I remember reading it about in the excellent The World's Writing Systems by OUP.
Resisting efforts to broaden literacy for the masses is also cites as the reason why the Ancient Egyptian hieroglyphic writing did not evolve much over the vast time period (first inscriptions around BCE 2800, last inscription dated to CE 394, that's more than 3,000 years!). Specifically, although they did have 24 uniliteral signs (http://en.wikipedia.org/wiki/Egyptian_uniliteral_signs#Unili...), which they could have used as an alphabet they never did so.
