There are two glaring problems you apparently can't see....paying less, that would be fine if the paying less part were across the board. You pay less via the subsidy, the premium isn't very much different for un subsidized insured, or private plans. As an added bonus, taxes are paid, by both subsidized and un subsidized insured, so the actual cost of providing insurance subsidies is added to the unsubsidized insured tax bill.
Under your public option would everyone pay the same rate?