Is There A Benefit To More Medical Care And More Health Insurance?

A comment I posted on Megan McArdle's Atlantic blog, Asymmetrical Information, "Firming Up the Argument" and on Marginal Revolution blog, "How many people die from lack of health insurance?" by Tyler Cowen. They both wrote about the lack of benefit of increasing health insurance coverage.

It is easy to change the cause of death, but it is very difficult to delay death. The major changes that have decreased mortality and increased life expectancy are farming (vs hunting), washable clothing, clean water, antibiotics and job safety. Most of the recent gains in life expectancy are probably due to better prenatal care than anything afterward. We are probably at the stage where the cost benefit is outside the medical field. Reductions in accidental deaths, homicides, and suicides would probably do more to increase life expectancy in the US than more medical care.

Are we at the point in US medical care where the marginal benefit to society from more health care no longer is greater than the marginal cost? Is there really a need for more medical insurance coverage? Maybe the reason medical care is getting so expensive in the US is that we are at the point in medical care where we have to spend more than the benefit, where each dollar's worth of gain cost more than a dollar.