˄Height advantage is HUGE in combat especially where you have range elements be it defense, accuracy, range, moral, everything it's the biggest advantage you can get combined all of those and you can stop huge numbers...
So i'm totally ok with a bigger numbers granted. I would be more happy if you could go prone to counter it but that would be asking to much just like overwatch. IF you were on ladder in the middle of nothing i would be fine with just range bonus...:)
As is, i know how important normal terrain height advantage is i mean +3 or whatever would be fine as well but that's not gonna fix the problems you have with combat. Because IF highground advantage is to big, then advantage it's to big for everything.
Due to the things i said before Hp and stuff... i was exaggerating a bit but still you get the point.
Like i said already they need to fix jump/disengage first before anything else. If you wasted 1 or two turns just to get to high ground no one would cry it's op.
But it looks like nothing is gonna change anyway so it's all pointless... and is just random forum fighting. So i'll use my Height advantage thank you and hope for mods and really hard and not a gimmicky Nighmare mode.
The main problem to me is not especially that "advantage is too big".
The main problem is that A LOT of tactical options (spells/actions/features) are now useless.
Those options are useless because something cheaper in regards of action economy give the same bonus.
I guess it would be fine if verticality was a part of very specific combats. You would still use faery fire and so on in other situations... But that's not how BG3 is build and I'm totally fine with it.
Keep also in mind that things has to be balanced because if stacked bonuses are too important, the %to hit himself become useless..
The easiest way to unlock MANY tactical possibilities and synergies between companions (without breaking the balance even more and keeping the verticality) is to remove the advantage to highground and rework it's bonuses so there are less meaningfull than advantages (+2 to attack roll + better range than the ennemy + better cover is huge enough according to me...).
But of course they could also rework every D&D spells/features/action that gives advantage to give them another utility or change their cost... But that would be very very risky for many reasons.
I'm not a game devs but it looks obvious to me that the easiest way is to rework 1 or 2 custom rules instead of all D&D spells and features^^