This is already a priority for us, but I can't promise a date yet. The Nightmare Mode system was originally built on the back of Hard Mode, which is why they share a lockout. It's a technical consequence of that fact, not a philosophical thing on our part.
Blessed are ye! Just knowing that it's a priority to get fixed is enough for me, honestly. The worst feeling in the world is seeing something really egregiously wrong with the game and not knowing whether or not the developers agree.