Americans are realizing that under the Affordable Care Act, many people will in fact not be able to keep their current insurance plans. That reflects poorly on President Barack Obama. But it doesn’t necessarily reflect badly on Obamacare.

Obama had no business promising that people who like their insurance would be able to keep it. The reality is that the federal government doesn’t have the power to prevent insurers from canceling or changing the plans they offer.

So Obama made a foolish promise he couldn’t possibly keep. Insofar as that argument was used to attract and justify support for the law, he undermined the political legitimacy of his signature achievement.

It may be too much to expect Obama to admit as much. But he should explain what he failed to make clear three years ago: Moving some people off their current plans in the individual insurance market, which is how about 11 million people get their health coverage, isn’t some unfortunate side effect of Obamacare. It’s part of the point.

The law sets minimum requirements for insurance plans. They must cover benefits such as maternity care and mental health care, for example, and provide preventive care without co-payments. Insurance companies cannot deny coverage or charge more because of a pre-existing condition.

The lack of such requirements is essentially what allowed insurers in the individual market to offer the cheap plans that are now being canceled.

Obamacare was designed to take that thicket of individual plans with variable costs and benefits and replace it with a smaller range of uniform products that people can compare on an apples-to-apples basis. The cost of insurance for many people will go up as their coverage improves, which is why the law includes premium subsidies for those who need them.

In other words, the individual market under Obamacare was always going to look dramatically different from what came before it. If it didn’t, the law wouldn’t work.

The benefits of reshaping the individual insurance market don’t excuse Obama for making a promise he couldn’t keep. At the same time, the fact that he misled the public doesn’t mean that the change now under way isn’t a good one.

At any rate, the real promise of Obamacare has always been as much about systemic change as individual coverage. If it works as planned, the Affordable Care Act will help millions of people get health insurance, and it will make that insurance more affordable for millions who already have it.

Bloomberg News (Oct. 31)