Sex selection is bad for society if the gender selected is highly skewed in favour of one particular gender. If in Australia, 1000 people use gender selection to create a boy while about the same number use it to select a girl, then there are no consequences to society. I don't see any reason to prohibit the practice in this case. However, I don't support the abortion of babies of the non-preferred gender.

China is a prime example where gender selection in favour of males has created a problem where many men will never find a wife.