Actually I would say WoTC wants to introduce more people to the actual game of TTRPG etc, rather than the ruleset. So it makes total sense to all BG3 some room to make it more appealing to the casual base. That is more people that can be brought into the D&D playerbase overall, where they can than deal with whatever homebrew 5E ruleset some DM wants, if even that. A lot of DMs stay with 2e and 3e.
That's probably the thinking -- can we introduce the game to new players.
But I think they will be making a mistake if they don't keep a close eye on the ruleset. If the ruleset is always in flux and the interpretations of it differ radically why go the license at all? Why not make something really similar -- which is what PoE did and it's what Pathfinder is doing. Someone needs to set the standard that other deviate from.
(and right now that looks like Solasta even though it's just an SRD game)
I think the main difference is this. Pathfinder and POE are marketing their 5e based game to established D&D players. People that are fully educated in the 5e ruleset and are trying to establish their brand as a major player in the field. Where BG is different. I think it has way more name recognition, and even people that have little to no experience with it, have heard of it. So it is the perfect title to bring in new people, rather than cater to just existing enthusiasts. So what brings in new people? Production value, story, and fun play. I know to a 5e player, when you see things like the jump, push, barrels it is an affront to your playing in TTRPG etc. But to regular, casual players, it is fun and engaging. They really have no idea what advantage/disadvantage is, or that this or that is not in the ruleset.
So I think BG3 has two things they want to accomplish, and I think some people need to consider this. YES, they have to base the game on 5e, and utilize the ruleset, but most importantly, they need to focus on the story of D&D, the mythology etc. Because that is what draws new people in. But at the same time, they have to put some "cheese" into it to attract the average player. That is something that I think this game does way better than PoE, Solasta or Pathfinder. Where the latter provides more accurate adherence to the ruleset, BG3 offers more attraction the the wider player base. I think WoTC is quite aware of this, and want this to happen.