Larian sells the game as a Baldur's Gate game and a D&D game so they have to stick to the rules. Minor changes are great because everything in the tabletop don't work in a video game but this is not supposed to be a DoS-Like (even if some DoS's mecanics are great and suits very well to the game).
D&D exists for about 45 years so yes, it's a bible and it looks like the 5th edition is really appreciated by role playing players. I trust them and I'd love this game to become a true BG and D&D experience.
