If we are going to consider by the way of virtue, a female child will grow and leave her parent house to marry another man and then this has always been the custom, while a male child will be the one to receive in a wife into the family, so they believe that the female child who marry to another man and family entirely has joined with her husband family and she will be bearing his surname henceforth while a male child will maintain his father name through his generation and remain, all these are the olden days customs some of our parents follows and the male child will be the bread winner of the family.
This is why in some tradition (especially in Africa) they prefer to have many sons than daughters to carry the name of the father (to me is just a name nothing more) and I don't think nothing is wrong to have a girl, in as much as she'll marry amd leave the house it still doesn't change the fact that she can't help out the family who raised her or it doesn't stop her from calling her father dad or mother mom.
If the girl child will marry and go out it still doesn't mean the boy child won't marry and start his family outsider his biological home, so for the family to grow and not to impose the pressure on "only the boy child" is bether to have a collective efforts from both the girl and the boy child, with that I don't see the pressure on the male child.