The problem is that doubling the amount of mobs or doubling the monster's HP isn't going to work when it comes to increasing the challenge. Difficulty doesn't just scale like that.
I mean, who knows, maybe they'll find a way. But I worry that the reality is that they're going to have a hard time making a more difficult game unless they take the painful step of nerfing the items and effects that *they themselves* inserted into the game.
I started a request thread before happening upon this one. By far the simplest fix, and one that would really enhance the D&D experience, would be to add a new difficulty setting that removes the metagaming information (hit chance percentages, enemy AC, HP, resistances etc). Then players would have to use their best judgement of which enemy to attack, pay closer attention and learn what an enemy's weaknesses are. Rather than being spoon-fed all this information that no sane DM would ever tell their players. RAW players should only know when an enemy has less than 50% HP, not what their total and current HP are.
If you wanted to take it to another level you could even remove the enemy names unless they've been introduced or revealed somehow. So players would have to assess who the leaders are by their appearance and behaviour – not just casually reading it.
I absolutely agree with this, and in fact I think its really a missed chance that they did not do this. Because this could also be built into the skill check system, and this game REALLY missed the mark when it came to making all the skill checks valuable. For example when fighting an animal, you could start out with no information, but a nature skill check might reveal things like its AC, resistances, vulnerabilities, etc. And you could use different skill checks for different creatures.
But while I agree this would help, it wouldn't solve the problem. Especially later in the game, the items Larian gives you access to are simply wildly imbalanced and really throw off gameplay. I actually bought up the idea that they should have different versions of items for different difficulties of the game - that way they could let them still be unbalanced at lower difficulties but tune them better for higher ones.
