Here's a good example for why weak enemies are needed (imo):
Imagine using a fireball that is a level 3 spell at an appropriate level (let's say 3 lvl 3 spell slots per long rest) and not killing anyone. Or using same fireball with a higher level slot and not turning your enemies into neat piles of ash. That's a feelsbad. And if we talk about going somewhat closely to DnD ruleset - spells have rather limited amounts of uses and require rest to replenish. It's not divinity where your only limiting factor is cool down and so gain.
Also if they want true DnD experience AP as we know it from DOS has to go. In DnD moving doesn't eat into your action count*, and characters have set amount of actions, bonus actions and movement they can perform each turn, as well as some ways to perform extra actions, reactions, etc.. That is of course if they actually meant it when they were saying that they want to be true to PnP and it wasn't just an excuse to put minimal work into gameplay.
For all cool things about DOS it never really delivered on power fantasy for me. My character never felt particularly strong, in particular due to the fact that there was no powerful high level spells that you could use consistently and very little encounters with weak enemies to draw out that engagement type. If game didn't tell me I would never really consider my character a god (in the end of DOS2).
If that's the level of power fantasy they want to shoot for (non-existent)it will be a pretty miserable DnD experience.