Obamacare was implemented as a form of cost containment in which the government would attempt to provide healthcare at lower cost or at least to stabilize cost. This plan has not worked and the cost of healthcare has continued to rise. The reasons this intervention did not work was because of the economic issues that are inherent in the managed care system.
Obama care was implemented in order to provide insurance for 15 million Americans who were uninsured. Most of these people could not afford insurance. Obamacare was also meant to stabilize the cost of healthcare and stop it from escalating higher.
Obamacare was supposed to be the answer to the rising healthcare costs, by placing limitations on the cost and providing government subsidy. The reasons that this intervention was chosen over market based solutions is due to the fact that the market has not been able to lower cost and continues to rise despite competition. Private companies have not been able to contain cost and have grown faster in cost and higher than managed care.