The view that if something is good or beneficial the government should provide or mandate it is one of the attitudes dividing those who favor limited government from those favoring a more expansive and generous government. The following provides one example.
Ivanka Trump and others make a convincing case for generous paid family leave, Paid-family-leave-is-a-good-national-policy. Stephen A. Schwarzman, Founder, Chairman and CEO Blackstone, explained that Blackstone extended its paid maternity leave from 12 weeks to 16 weeks because it improved Blackstone’s bottom line – Paid-maternity-leave-is-worth-every-penny. But for all of the many reasons that big government should be resisted in general (inappropriate incentives for government bureaucrats and the public, special interest capture of policy—i.e. crony capitalism and other forms of corruption, limitations of individual freedom, inefficiency, etc.), there is not a good case for the government to get involve in mandating or subsidizing paid family leave.
Generous paid family leave programs provided by employers are smart business. Companies that offer them will have a competitive edge and thus free market firms will increasingly adopt them. Employers will be free experiment with what works best (for employees’ and companies’ bottom lines), which may well evolve over time as markets and technology change. Governments’ rarely enjoy such flexibility and are often captured by voters best able to influence government to protect their special interests, and that is never the poor. Those who are unemployed don’t need paid leave as they are already receiving unemployment compensation or welfare support for staying at home.
Maternity or family leave has facilitated bringing women into the labor force and thus increased family and national incomes. Given the importance of education to worker productivity and thus individual and national incomes, the state has also undertaken to finance (and unfortunately in most cases also to supply) education for all children from Kindergarten to 12th grade. While upper income families can easily afford to pay for this education for their children, lower income families generally cannot. Thus public financing of such education helps give all children a more equal start in live and also facilitates two worker families. A gap in such assistance exists for preschool children (age 0-5). Financial assistance should also be considered for day care or nursery schools for such children.
In most cases where a policy or practice is good for the general public, it will be adopted by free market participants and better fulfill its purpose than is possible or likely by government.
Warren's space 
You write, “Generous paid family leave programs provided by employers are smart business. Companies that offer them will have a competitive edge.” But this is a hypothesis, right? Maybe workers would prefer cash, or health care, or some other form of compensation. So we will assume it is good business if firms adopt it. So I think I’m agreeing with your main point, just suggesting that these sentences seem to claim something more.
Ivanka would also need to Trump-up some Constitutional interpretation for Federal interference.