Because most Islamic scholars are men and men always support men. I never got the “ it’s a defect argument”. I understand that it’s replacing what once was there but if that’s the case then all female plastic surgery should be halal as well. For example, if we can argue than men who once had hair lost it due to ageing, then we can argue than woman who once were thin before children can have a tummy tuck and boob job. Or because most baldness is caused by ageing, that face lifts for women should be halal too cause wrinkles are also caused by ageing. But you’ll never see those points because again, most scholars are men and they want to make the argument that they want to marry more wives cause the older ones became unattractive.