It does not really matter if parents choose not to go back to work at all or to go back part time after their parental leave.
It just means that society would stop seeing making babies as the mother business. It would be a parent business as both parents would be entitled to paid leave.
So small businesses might stop promoting a male worker over a female worker for fear of maternity leave since male workers would also be entitle to the same leave.
Talk about equality
In my perfect world, after both parents have taken their parental leave, they would both go back to say 3 or 4 days a week. That would be sweet. But really, who cares, each family would do what's best for them.
ETA : VP you could take unpaid leave after the first 3 months. Or you could take your leave at half pay. I think it is possible to go back to FT work (if that your choice) and keep up BF when bub is over 6 mo. That's my plan anyway
ETA 2 : I must stress that the issue is not how to get people back to FT work after baby but more how to stop society seeing that having a baby is a mother's only business.