I'm the first to admit I'm quite ignorant of my own history, let alone the economic history of Korea and Japan, but surely you aren't suggesting that if we keep buying stuff from China they will turn into a rich country and magically increase the working conditions?
It's not really magical, but yeah, that's how it's always worked.
Yes, someone has to actually fix the working conditions, but it's not going to be you or me, it's going to be the Chinese workers themselves. American and British workers formed unions and engaged in often violent struggles to improve pay and working conditions; some enlightened industrialists like Henry Ford voluntarily and profitably improved pay and working conditions on their own as well. The same thing will eventually happen in China as soon as the country has enough wealth to bargain for. It'll probably happen easier because the Chinese can learn from our history.
Outsiders can't fix them directly, but they certainly can bring pressure by publicizing things like this and pushing for change at the WTO and other fora.
Basically that's how it's worked for everyone else.
And that's working for China. As has been pointed out -- 12 hours in a factory beats 16 hours in a rice paddy. These people aren't slaves -- they are working hard to secure a better life (mainly for their children).
It's actually already happened. Most of the really nasty stuff (electronics recycling, sweatshops, etc) is now happening in places like Bengal and Sub-saharan Africa.