The mistake you're making...
Is assuming this is all about making sure people have good medical care. It's not. It's about shifting a huge amount of power and money into the government.
Never mind the shunting of immense quantities of money out of the private sector into the state coffers. Once the state controls medical care, what aspect of your life will be beyond their legitimate control? "We're paying for your medical care, so you can't (insert favorite vice here)." This is already used as an excuse for things like helmet laws, seat belt laws, smoking laws, and others.