But by endorsing and expanding the complex new policies promoted by the health care industry, the law may in some ways be undermining its signature promise: health care that is accessible and affordable for all.

“I’m always curious when I read this ‘good news’ that health costs are moderating, because my health care costs go up significantly each year, and I think that’s a common experience,” said Mark Rukavina, president of Community Health Advisors in Massachusetts.

While much of the focus in the past has been on keeping premiums manageable, “premiums now tell only a part of the story,” Mr. Rukavina said, adding: “A big part of the way they’ve kept premiums down is to shift costs to patients in the form of co-pays and deductibles and other types of out-of-pocket expenses. And that can leave patients very vulnerable.”

Such policies desperately need improvement, patients and professionals like Mr. Rukavina say. But with the Republicans attacking the Affordable Care Act at all turns, even political supporters seem reluctant to acknowledge that it has some flaws. The narrative has been cast in black or white: It’s working, or it’s a failure. The reality, of course, is gray.