One of the main reasons ACA is more expensive than it should be is because health insurance companies are jacking up the price. The insurance companies are surplus to requirements, once the US gets rid of them (and cuts down on price gouging by the pharmaceutical industry) the overall healthcare costs should drop dramatically.
Back in my native New Zealand, the total income tax for an average household is about $6,000 USD. $14,000 just for insurance vs $6,000 for "free" healthcare and all of the other infrastructure a country needs.
The US healthcare system is a joke. A joke that wastes money and costs lives.
I took my kid to the doctor recently and a 15 minute appointment was $250. It doesn't cost $1,000/hour for a doctor to do a routine exam.
Part of the problem is the US is that the actual cost of insurance is buried in your benefits so people think that the $200/month they pay is the cost of insurance.
The best way to move ACA in a progressive direction would be to have a large public player in both insurance and as a provider.