That link you posted is making my browser give me warnings by the way.
Also a 3.5 averages to 4.
Weird, Wolfram Alpha has never given me any warnings, be it from private or company network; you can google it, it is safe.
And no, 3.5 does not average 4, I cannot even follow what idea you had here.
It's 3.5 if you don't account for critical rolls, Natural 1's always missing and Natural 20's always hitting bring the value to +5.
Wrong. If you don't have a clue about a subject matter, don't try to lecture people who do. I admit I did not account for criticals, but that effect would be negligible, especially considering criticals will often deal overkill damage (Goblins).
The +5 comes from assuming a 50% chance to hit. That means that you miss on 0.5*0.5=0.25 (or 25% of the time) and you therefor hit 75% of the time. This is equivalent to +5.
Now, you would be correct in pointing out that this is the maximum benefit possible from advantage. It declines as you both raise and lower your chance to hit. It does overestimate the value of advantage a bit.
However, it is almost certainly a better estimate than assuming an even distribution of hit chances. In a well balanced game you will not see very many situations where you hit on a 2, or very many situations where you only hit on a 19 or 20. Given the actual to-hit chances that you will encounter in BG3 the value is probably between +4 and +5.
In my gaming experience, the base chances to hit were generally way above 50% (at this moment I can't pinpoint a number, though). It is very well possible that Larian adopts a "missing is boring" stance, so we get something like a 80% base hit chance on average. In that case, advantage would only translate to +-3. I think assuming an even distribution is as accurate as we can get until the numbers are tweaked.
I would have to disagree, I think height advantage should work with ranged and spells. It is taking advantage of 3D space, rather than 2D tabletop. But, I don't think say you on a small ledge just behind someone, and it gives you a melee advantage. That just doesn't sound right. There should be a slight benefit for ranged classes considering how OP melee classes seem to be. I have played a warrior, rogue, hunter and now playing a warlock, and melee definately have an easier life and do more damage it seems.
Some are offering a compromise because the current state is just too advantageous. Height gives roughly +4 to hit and +4 AC vs those who are below you. I don't know if you are familiar with 5e but one of the main design aspects of 5e is bounded accuracy. The goal was to reduce bonuses so it would be manageable all the way to level 20 and bridge the wide gap that often appeared between high and low levels. So at level 20, characters get +6 to hit vs +2 to hit at level 1. It's not a big gap, certainly not as big as previous editions.
From my understanding, BG3 will cap roughly around level 10. That would mean +4 bonus along with your bonuses for ability scores and magic items. As you can see giving +4 bonuses so easily can disrupt combat balance (you are doubling proficiency bonus at level 10). Other tactics are tossed to the side. It just becomes a mad rush to be on top of the hill. It' doesn't make for more tactics. It reduces them.
So some are asking for +2/-2 or even just -2 for height disadvantage. I don't even like that but either compromise seems better than what we have now.
Height advantage adds a tactical layer (terrain) to the game, which similar games like Pillars of Eternity or Pathfinder Kingmaker simply do not have at all, which is a good thing in my book. This, of course, has to be impactful, or most people will just ignore it. Seriously, would you bother with high ground if the only effect were +2 AC?
