A lot of people, including former White House spokesman Reid Cherlin, seem to think it's extremely difficult to explain and defend the core elements of the Affordable Care Act to people:
Whatever its downsides, the Affordable Care Act delivers some pretty serious benefits: tens of millions more Americans covered, no more getting dropped because of pre-existing conditions, closing the Medicare donut hole, slowing the explosive growth of health care costs, and on and on. It's just that it's so goddamn hard to explain the thing—whether you're the guy answering questions from reporters or the guy answering questions from the nine justices who will decide the bill's fate.
It's true that the law covers a lot of ground and that if you want to explain each and every provision you're in for a long afternoon. But as a journalist who writes a lot about public policy, I don't think that the main element of it is nearly as complicated as the Obama administration has convinced itself it is.
The issue is that they wanted to ban insurance companies from discriminating against people on the basis of their health status. But what people who've enacted this kind of non-discrimination rule on a state level have found is that this pushes premiums up too high because nobody wants to sign up for insurance until they're already sick. So the government will fine people who don't pay into the system, but also will provide tax credits to make sure it's affordable for everyone. The legal issues are (a) does Congess have the authority to regulate the insurance industry in this way, and (b) do they have the authority to take the steps they deem necessary and proper to make the regulations work?