With almost 30 years of government encouraged and bred competitiveness to exceed in life via a good career and material wealth. Our rat race starts from the nursery and all the way to retirement. To be socially accepted, one must first have a good career and etc. Thus these place additional stress and worries on married couples. Stress plays a big role in infertility and breaking up of the family unit. So if this is not arrested first, most couples who are on the verge of a marriage breakdown, would be tempted by this carrot (Baby Bonus) and see having a baby as a marriage saver or a temporary solution to their debts. They will only be adding to the number of trouble youths from divorced parents further down the road. Which is what should be avoided at all cost.
Also most able bodied couples are too busy working just to be able to afford the minimal standard of a comfortable lifestyle, this coupled with stress from work, family, etc. Fear from the unknown rising cost of maintaining a family. So just by introducing the Baby Bonus, it would not be a long term solution. Lowering the cost of living, cost of maintaining a family and work stress must be seen too first. So that the baby Bonus would not be just a novelty with it's temporary effect.