In theory, one way to control costs and improve reliability of health insurance would be to impose a tough regulatory regime on the health care market. If that were possible, there wouldn't be as much need for a public option.
The problem is that the theory is ill-suited to practice in the United States. In many policy areas, our politics is like a pendulum. A prime example: the swings between regulatory and deregulatory fervors. Right now, the country is in a pro-regulatory mood. But in the not-so-distant past (think Bush II) there was a strong push for deregulation.
Imagine if instead of being constituted as government programs, Medicare and Social Security had been constructed as highly regulated insurance and retirement pools, respectively. Is there any doubt they would have been completely destroyed in the 1980s under Reagan or in the 2000s under Bush?