I don't understand how this isn't being talked about as a solution.
It is being talked about but there is significant opposition from those that don't want to raises taxes to the level that would be required to finance such a proposal.
It could end up being a cost savings overall, or at the very least be cost neutral. Most people are paying for health insurance now anyway. If that shifts from a premium paid to your insurer to a tax payed to the government is that really a big deal?