Why did Mine get a "you may", but not Remodel?
Presumably because the old Mine is cheatable, but Remodel is not. Specifically, you can play the old Mine and say "I don't actually
have any treasure in hand"; there's no "or reveal a hand with no Treasure" clause to prove you right or wrong. With Remodel, it's public knowledge that you do (or don't) have an additional card in your hand, so there's no way to cheat its play. (I know you know this, but for newer players, this matters for things like Conspirator and Peddler that care about the number of actions/action cards played in a turn.)