Mandated insurance purchase for everybody is a terrible way to provide universal coverage. It may be the best option open the US right now because of the ideological opposition to any large government program, political opposition from Republicans and the massive amount of lobbying money being thrown against it. But it isn't a good one in any sense of the word.
The insurance field is inherently not a good market. It's very difficult for the insured to get good information comparing their insurance to other insurance and people don't tend to care enough until they need their insurance and then then it's too late to shop for the best price/benefit ratio. The one in the US is even worse because it's normally purchased through your job not personally. That greatly cuts down on the competition in the market and keeps people from realizing just how much it actually costs them. The end result of that is that any market place solution is not really going to achieve the sort of cost containment desired.
Jay