Describe the solution you'd like
There are no fee refunds in Optimistic Ethereum, meaning that gasPrice * gasLimit is the fee that is paid to the sequencer. We need to make sure that the values returned from eth_estimateGas and eth_gasPrice are very accurate for this reason. We should not accept transactions that are very mispriced for this reason. Note that there is no auction for transaction inclusion, the sequencer includes transactions based on "fair ordering" or in a "first in, first out" manner.

There is currently a bug in eth_estimateGas that causes it to fail when it shouldn't. We cannot use a gas estimation to prevent accepting overpriced transactions reliably until we fix this bug.

See: #661 (comment)