Outside of personal reasons, the most likely reason to consider moving to China to take a job would be the impact that such a move would have on one’s career development.
China appears to be the next big player on the international scene. It appears that it will be important to businesses around the world for some time to come. Because of this, it could be very valuable to go to China. A person who goes to China to work would gain invaluable experience with regard to how business is done in that country. They would gain contacts in China. They might even learn Mandarin or some other important Chinese language. All of these things would make such a person a much more valuable potential employee for firms in the West that wish to do business in China.
Therefore, taking a job in China could improve one's career prospects.