The US has some of the highest entrepreneurship rates in the world despite having a pretty weak government provided social safety net.
People would be far more likely to start a company if it didn't mean giving up their existing healthcare benefits and having to pay for it out of pocket.
Sure it would cost less, but then I'd be on the same insurance as everyone else. That means worse quality of care for those of us who currently have something other than Medicare.
I'm not sure the US model for primary care is that great either - there have been many articles about how medical clinics are now pushing people through in 10-15 minutes instead of taking the time to fully understand the patient's needs and avoid over prescription. A routine visit for my kid at the local clinic (Allina Health) is now $150 - $190 (for a 15 minute appointment to check for something basic that a PA at Minute Clinic wouldn't touch). That same visit back in my home country cost $43 USD (non resident rates).
I'm not sure there would be a significant drop in primary care for most people?
This part still bothers me after 10 years in the US. Health insurance might as well be a tax if you have a family or any ongoing health issues. Hearing people say "I don't support universal health care because my taxes would go up" drives me insane. If the proposition was higher taxes but less overall money spent on healthcare then it's a net gain for you. Of course there would still be many issues to resolve (is it 100% public or a public/private mix, how do you control costs, how to you serve the massive rural areas here, how to manage the job losses from removing insurance/billing from the industry etc) but tax increases is a shitty reason not to at least look into it. It also amazes me that the same people opposed to tax increases aren't the ones screaming to remove the burden of health insurance from employers.
There are many things I love about living in the US but I am still often amazed at how much the US accomplishes despite some of these barriers. Perhaps I am naive to assume the US would be even more dominant in the world if we could sort out basic issues that other countries seem to have already resolved.