This is one thing I think many WoTC adventures struggle with and I don’t think it’s a new issue. A backstory is often provided, “this house is spooky because 100 years ago a wizard…” but there is no way for players to learn any of that unless the DM has a book fall from the sky or an NPC show up and recount the history. Neither of these is pre-written into the adventure because I suspect the writers know it would be weird.
Fundamental to RPG adventure writing as opposed to regular story and novel writing is that the history has to be (should be) discovered in play. It’s hard to do, and often not done because the history doesn’t exactly matter, monsters attack, deal with it. But it’s so much more engaging if why those monsters attack is known. Showing, rather than telling (and often only to the DM and not the players) that reason is sorely missing.
I suppose one could argue that weaving that engaging history throughout the encounters limits the portability of the adventure, but i’d argue it doesn’t. Even if you want to entirely replace the motivation and backstory, having a clearly presented way for the players to slowly discover it gives the DM a map to inserting their own history and motivations.