One of the reasons why liberals were upset with the Affordable Care Act is that there was no public option and that consumers were forced to buy a private product without a public option. The public option would have created even more competition for insurance companies and would have been a better policy overall.
While public health insurance is necessary to keep down the cost incurred by hospitals and emergency rooms and to provide health care to everyone, a hybrid public-private health care system would allow citizens the option of more choices in their healthcare. Mexico has this type of system in place and it works very well. Those who choose can elect to be treated in the public system at little cost but everyone has the option to seek private care.