Yeah, I'm all about this right now, but what about these Difficulty Level Settings:
1. Story Mode = Backstab, High Ground, Barrel Throwing, and all the things we have now. Loaded Dice by default, more inspiration points by default, unlimited long rests, etc. Game doesn't change much from current state except maybe more inspiration points handed out like candy at Halloween for those who hate failing on dialogue rolls and inspiration can be used for combat too so players can gain extra help in combat. Also, maybe less enemies in various areas like the Necromancer Lair, Spider Lair, etc.
2. D&D 5e Mode = Actual 5e rules implemented. No backstab or higher ground, etc. Potions are Actions. No food during combat. True RNG. No loaded dice. Enemies have true 5e stats like accurate HP and AC. Disengage is an Action. I mean full blown D&D 5e experience. Game is harder because it is full blown rules with no cheese and nerf.
3. Dungeon Master Mode = Like 5e except even harder for those who are insanely good. This mode would be for people who truly know all the weaknesses of every enemy and they can exploit them really well. More enemies with more HP and AC and so forth.
Why would you remove highground ? What would be the point of taking a good position in your system ?
Of the 3 listed options I'd probably be playing on #3 DM mode myself if those were all that was offered. I would love to see a more detailed options menu like that in the post with Solasta's menu though. I would much rather have options built into the base game than have to mod it in later.
I do want to comment on "the point" of taking high ground even if there was no innate mechanical advantage applied for doing so. Even though it is not 5e, I can see the argument for an increase to the range for crossbows/bows due to simple physics but personally feel/will play with no bonus is needed. Holding a higher position is already a tactical advantage in a few ways.
1. Shoving/blasting an enemy so they take fall damage is obvious and there are multiple ways to do that, everyone gets at least 1 in the form of the Shove bonus action. Changing the Shove option from bonus to full doesn't change the fact that fall damage itself is no joke in BG3.
2. Limited access/choke points. Whether it be a ladder or a stair like structure built into the terrain getting squishy toons to high ground allows you to use a tankier toon or 2 to hold the access route and keep the enemy's melee off your peeps.
3. LoS manipulation. In many places if I'm on higher ground I can fire down at an enemy and then move back out of their LoS so they can not return fire. You can add going into stealth with that but often isn't needed so long as you have enough space on your level to just back up enough the terrain blocks any return fire/spells and abusing the stealth in the game is a bit cheesy to me so I don't bother.
High ground is already the better position before you start adding game mechanical advantages to that.