The purpose of the Nightmare Mode expansions, as I see it, is to pacify the players who are constantly complaining that the game is too easy. A secondary reason may be to quietly assess the level of interest for very hard scenarios; if they sell very few of the Nightmare Mode expansions (as I think likely), then they'll know how many players are interested in that difficulty level.
At the risk of being cynical, I don't think it will shut down the complaints. Every relatively easy quest that is released - every single one - they complain, as if they expect every single quest to be Difficulty 11. The idea that that may not be what all players want completely escapes them.
But at least now there is a reasonable response: think the recent quest is too easy? Have you beat Escape from Dol Guldur in Nightmare Mode with your solo deck yet? No? If what you want is difficulty, then why are you playing recent quests that you know will be less difficult than the Nightmare Mode quests?
A few things I'd like to address on mine and the coc community's behalf:
1. It would be nice to know if Terror in Venice is going to be out and legal for tournament play at gencon, considering gencon is less than a month away!
2. An update to when the players should be expecting new story cards would be nice
3. An update about the reprint of the dreamlands cyle would be nice