I suspect the higher levels of dissatisfaction come from a different source, one that has different policy implications: Unlike people on Medicare, Medicaid and employer-based insurance, people who buy coverage in the individual market know exactly how much they’re paying for it. A plan that you would only rate “fair” when you have to pay $5,000 for it might merit an “excellent” if its apparent cost to you were only $1,000.
Look, the groups of people not mutually exclusive. People who have employer, medicaid or medicare insurance quite often have had to go without insurance or buy their own on the individual market. Lay-offs, no coverage periods between jobs, etc. So personally I suspect many of those people who are satisfied who have medicare, medicaid or employer plans know how much it costs and are glad they can get it subsidized or earn pre-tax employer benefits. I suspect many of the 45% of folks who dislike their plans on the individual market actually had to use their benefits and found out they were paying for nothing of any use.