Well at least now that they are working in the Forgotten Realms lack of world building will not be an issue at all 😉
We shall see. Drawing from existing lore without properly introducing it ingame might be a problem in itself. Thats an issue even some original games suffer from (looking at you, but with an affection, Pillars of Eternity).
Bioware did an excellent job in using existing FR lore and characters without feeling off to a complete new comer (like myself). Everything had either a strong set up, was a flavour detail which gave an impression of wider world, and was a nice detail for folk familiar with the source material, or was driven by a strong, relatable central narrative, allowing to accept weirder stuff.
Outside Torment, I never felt it was achieved quite as elegantly in other games. I remember watching early Marvel movies, and coming out with "WTF was that thing or why did that happen" to be explained it comes from comics or is building toward something, but never quite fitting in the currect narrative. I never had this feeling with BG1&2. I might not know who Drizzit was, but his apperance worked.
The important thing, in terms of involving a player with a game-world, is to be aware that a player may know nothing at all about the world, or may know everything about the world. That can be tricky to handle.
The best way to deal with these extremes is to only force the minimum information about the current situation into the story, but allow ample opportunity to gather lore concerning the wider world geography, history, religions, politics etc, through optional dialog, books, inscriptions, paintings, carvings and other in-world information sources.
From a personal perspective, I find access to maps to be invaluable to make sense of a game world, and time-lines can also be helpful. Clearly, making information you discover available for later cross-reference is also important.
Unfortunately, many developers do not pay enough attention to getting this right, and their games suffer for it.
