The argument that 'BG 3 doesnt need to be 5e rules' is nonsense. Its saying 'we cannot use 5e rules as the game will reach less people' but that is neither provable, nor remotely likely at all.
You want to reach people who are interested in Baldurs Gate? Well other than a cheap name drop (check) they could implement the rules that are current. 5e. You want to reach people who are into D&D now? 5e. You want to reach people who are into turn based games with depth? Solasta proves what? 5e. You want to reach people who play video games? Well...they dont care, they play whatever, so no harm in guess what? 5e.
Honestly unless the next update says 'we hear you, we will fix things and get closer to 5e' then its just an admission of lack of effort. They never tried. Its not like they built the game into 5e and cut back. No, they built on top of the engine and rules they are already used to.
Its PAINFUL levels of obvious.
Either implement the rules set appropriately, or make sure mod creators can do the job for you after the fact.