would that be due to the design of the overall encounter has high ground availability? if one can just easily climb 2 feet up a hill to get an advantage would probably also mean a design encounter issue. or this could also mean that d&d5e ruleset does not translate so well into a game. but d&d is d&d. changing the ruleset basically means it's no longer d&d. also, is that a technical issue where half-cover could not be implemented? just curious.
Partially it's due to encounter design, yes, but I don't think it's an
issue. A big limitation of PnP D&D is that verticality is hard, both to represent on a 2D battlemap and it adds additional math/bookkeeping. A video game solves all of these issues, and so BG3 would actually be worse if it didn't make use of high ground. It was always the High Ground Advantage (HGA) that was the problem, not the high ground itself.
Adding bonuses for things (even adding Advantage) isn't "changing the ruleset." The DMG (PHB?) specifically notes that the DM can grant Advantage for certain situations, which can easily be extended to giving a smaller flat bonus. The problem, again, was that HGA was so easily obtainable and so powerful that it overwhelmed many other things.
As for cover: the way I see it is that BG3 suffers from: a) not being on a grid and b) from every part of an enemy being targetable. Thus, to determine the amount of cover gotten (none vs half vs 3/4 vs total) BG3 would have to calculate every single possible path from you to all parts of the enemy, then report on the % of enemy that you can draw the projectile path to. That percentage would correspond to cover. This sounds a bit computationally expensive. (Whereas Solasta, on a grid, can simplify the calculation because everything takes up a whole 5x5x5 block. Thus you only have to draw a line from the center of your block to the center of the target block: if object in the way = full cover; if person in the way=half cover). BG3 would then also have to change the targeting system - otherwise people would complain about the enemy getting cover bonuses even though they can clearly draw a line to e.g., the enemy's hand.
