>"How you would have designed their communication, if you had been the person in charge of crafting Larian's communication policy ?"
First of all, if the person who's in charge of Larian's communication policy and the person who's in charge of creating the game itselt are not the same person, it's going to be bad either way - like what we're having (or better say not having) now.
Secondly, I'd run things like the main guy behind Ashes of Creation does (it's a mmorpg in the making), VERY trasparent, participates in a lot of q&a's, interviews with streamers, he even explains stuff in the comments under other people's youtube videos. But you can do it only if you're the main guy behind the game as a whole.
Now it's too late to actually communicate. They would put themselves under an avalanche of high quality and harsh critique from different sides (because they tried to cater to differet audiences, and did it poorly). It would be ok 2, better 3 years ago. I don't think they can change much (if they could, they'd make a good game with alive world and day/night sequence from the beginning), so the critique would only attract attention of people (who otherwise would simply buy the game because of marketing) to the problems and potentially lessen the sales.