In the skull/lizard person example, can you extrapolate on why “this creates so many questions” is a bad thing? Is the goal to have no mystery in the games, and somehow this makes the game better?
Mainly it can be overwhelming during character creation, when you have so many things you're not familiar with. It might be that you don't know what your characters race is about (i.e. the skeleton guy), or when a game gives you cryptic stats where you have no idea how they influence the game. Things like that.
I'd say a good type of mystery is, when you're familiar with a setting and its characters, and then something unexpected happens and you're wondering why. But that requires a baseline to be established. Which requires either that the player spends some time with the setting, oooor: if the setting is so generic that it's familiar to begin with, it has its merits too, which I'm arguing for. :)
A good example, though not a game, is the manga / anime Frieren Beyond Journey's End. It basically starts where the most generic fantasy story would end: A party of heroes, including your typical cleric, elven mage, dwarven warrior have defeated the evil demon lord and are returning from their journey. Because it uses so many established tropes, you immediately have an idea about what the story leading up to the first chapter would have looked like. The interesting things are then how it goes on from there.
Divinity has always been a niche series, partially due to the small studio’s lack of advertising and smaller budget, but when you piggy-back off an already highly successful series, you would expect a higher adoption rate; which is exactly what we see with BG3.
Valid points with the lack of advertising. BG3 also had little advertising, but it got such a lot of word of mouth, it overshadowed all of that.
It's hard to say what would have happened if it had been almost the same game, except without the DnD license. I'd tend towards saying that if it wasn't Baldur's Gate 3 and not DnD either, but something very close in rules and setting, it could have piggybacked—not of the established name, but off the tropes that these names (DnD, BG) have established.