We relatively poor foreign teachers who marry Chinese nationals, and sell USD, GBP, etc to bolster our spending power in the country, even buying a Chinese apartment, are not treated that well! There are too many obstacles placed in our path if we wish to get long term residency rights. Another way might be to change nationality, but surprisingly that's also fraught with difficulties.
I'm glad to say that the Chinese govt has trapped itself between a rock and a hard place due to their lousy residency rights policies. They don't want to grant long-term residency rights to foreigners who are relative paupers compared to the rich ones. But at the same time they have to offer sth to avoid compromising foreigners' rights too much, which would lead to international condemnation. Hence the L visa for visiting your Chinese relatives. Some of the hierarchy in the Pubic Security dislike that system. They are well aware that it is abused by some foreigners who dislike RP's and like to buck the system by teaching with L visas, assisted by corrupt agents and dishonest employers in the field of education. But if they get rid of the long L's, what will they replace them with? That's their dilemma!