That poll doesn't say they're happy with their health insurance, it says they're at least somewhat satisfied with the coverage. You'd see very different results if you asked about health insurance prices.
I believe most people would incorporate the value received into their satisfaction rating.
Most people also don't have any idea how much their insurance costs in total or how it compares to alternatives, so that would be a challenging question to write with any reasonable expectation of getting a coherent response.
> The problem is the cost.
You could say this about almost anything that isn't free, and could still say it about a number of things even if they were free.
The problem is the cost.