Earlier quoted context omitted.
Moving to a single payer system would unleash a lot of latent entreprenurial activity and free companies of all sizes from having to provide health insurance. Great documentary here on the business case for moving to single payer: http://fixithealthcare.com/
I think part of the problem in the US is that the current status is so bad, that everyone has a different proposed solution. Single payer is also seen as too paternalistic by a large minority of the US, so there is that as well.
There is a reason why ACA messaging from Democrats always included the fact that you could keep your existing insurance if you wanted.