Childless women earn just as much as men. Forcing fathers to take family leave does fix the asymmetry between parents (mothers vs fathers), but will exacerbate the difference between parents and non-parents by penalizing not just mothers, but also fathers for having children, vs. non-parents who don't (need to) have a career break.
I think that no discussion/policy about parental leave is complete without some kind of incentive for people to have kids (or a discussion about whether we should encourage that at all or not - looks like it might be sensible in Western countries).