You make quite an assumption there as to why WotC didn't give Larian the licence to BG3. If WotC was concerned about faithfulness of Larian's adaptation of their system then they would put it in the contract. There is no indication as far as I know that WotC is in any way unhappy with the direction Larian is taking the game. If anything D:OS2 convinced them that Larian was the studio to make BG3.
Even if WotC had reservations or concerns about Larian's interpretation of the game, they certainly wouldn't make that public. Regardless, I assume they are ok with things as they are going presently.
