There seem to be two separate discussions happening: unit of account at the cultural layer and mental accounting at the buyer layer
I agree with 6529 on the core point: NFTs are crypto-native assets and marketplaces should denominate them in the underlying chain token
But how buyers evaluate a purchase in ETH vs USD depends on long-term intent, ETH cost basis, trading success, risk tolerance etc.
Ask two people whether they would rather buy a Punk for 30 ETH ($110k) or 35 ETH ($80k) and you might get two different, rational answers
