I beleive its because they are better accepted in society and can earn more money for the family.

That is not a very simple question to answer. First you must understand the Asian physcology that affects this. 1. Asian are, as a rule, a male dominated society. Having boys as heir brings prestige to families even in this modern age. 2. Even in these modern times it is assumed (wrongly) that weak sperm gives birth to females. Hence male offspring is desired to prove one's manliness. (Surprisingly this is true even in an advanced country like Korea). 3. Asian economy till recent times was basically subsisting on agriculture. Hence more the no. of helping hands (strong male hands) better is the farm produce (most countries still use labour for farming). Hence desire for male offspring. 4. The age old custom of dowry has done its share. This bad custom still persists wherein the bride's father has to shell out huge sum to pay the groom for marraige and also bear all the expenses of marraige. 5. One fact must be understood that even today most son stay with their parents througoht their lives. Hence parents desire an offspring who will "see them through" during their old age. Daughters wed and go away to their husbands place. Hence again the desire for male offspring. Hope this suffices for now.

To carry on the family name.

A wife is a sex partner, a maid, a bread-earner, a mother, a child-carer, a parents carer. A daughter will become a wife once she is married. A woman is not supposted to be single without a man in China.