The game doesn't need a new difficulty, what it needs is to stop allowing long rests in the middle of dungeons or dangerous areas. Without being able to reset your spells and abilities with a long rest after every fight you'll have to be much more careful with how you manage your resources thus making the game more challenging.
I'm not against limiting long rests.
But I don't think that's the only issue. For instance, I happen to be playing a warlock right now in Act II. It's occurred to me that I don't need to long rest. I keep going and going. The Angelic potions that count as a short rest are plentiful. Arcane recovery potions aren't running out. Every time I start to think I should long rest, I realize I don't actually need to.
I am rolling over these fights. I took out the drider in the first round of combat. I took no damage fighting Gerringothe. I got hit once fighting Malus and the undead nurses. I took out the gith patrol. I freed the tieflings and gnomes and got rid of the bottom floor villains at Moonrise Towers. I've finished the mason's area. I literally just finished protecting the portal for Halsin, and afterward, I didn't even need to heal.
Something is seriously off with the difficulty.
I'm not attacking from stealth. I start the dialogue and wait my place in initiative, that's all. The "cheesiest" thing I'm arguably doing is using the luminous armor gear, generating radiant orbs.
Again, something is seriously off with the tactician difficulty level.
