Let's not forget System Shock Remake which every big outlet seems to have forgotten about the existence of...
Multiple themes, switching themes, transforming or subverting themes are not in and of themselves hallmarks of poor writing
It's not that, it's specifically that the game seems (seemed) to have an idea behind the plot but it's not even subverted but outright flushed down the toilet because they couldn't bother with how they've handled the Emperor and the tadpole powers. A really sloppy mechanical implementation has managed to heavily cripple the plot, or vice versa. It's like if the whole spirit hunger mechanic from NWN2: MotB was just a source of flashy abilities and not a terrible curse that would irreversibly corrupt the PC if they gave in to it.
To add: there is a fundamental problem regardless of the sauce it's under, and it's that the tadpoles as an issue are completely divorced from the companions' storylines and really the entire plot outside of moments it remembers that they exist. We have plots like, again, NWN2: MotB where every character embodied some aspect of what it was about (dreams, mechanics of souls, spirits and their way of existence, faith or lack thereof...), and Torment, and, hell, even Larian's own
previous game to some extent.
In EA every companion's dream person was allegedly deeply tied to them and their insecurities, weaknesses, and hidden desires (for a custom PC those amounted to power and hanky-panky, with any hopes that it gets in any way developed dying together with Daisy). Lae'zel's was Vlaakith, Shadowheart's was her old (boy)friend (who in the main game seems to have been turned into Nocturne...?), Gale's was Mystra and so on. Given the premise of the "loss of self" and everyone having a moment where they are inches away from their worldview or their grasp on themselves falling apart, wouldn't it have made perfect sense for said desires and weaknesses to be used as a way for the tadpole/Absolute to try to sway them over? Lae'zel could become the ultimate warrior of her people, Shadowheart could get revenge on Shar's cult and Shar herself... Cue having to convince them otherwise or watch them succumb, and it resulting in a split of loyalties down the line when the time comes to pick the side.
As for the lack of planning, it's hardly the first time in the past 10 or so years that Larian seem to rewrite their games almost from the ground up rather late into development. Dragon Commander was supposed to be a sequel to Flames of Vengeance originally, and its final form suffered from a lot of cuts and awkwardly stitching together what was there (the final act and the endings were VERY underwhelming and underdeveloped). D:OS1 was meant to be about the origins of the Black Ring and Zandalor (and, I assume, delving into the mage wars described in the older games' lore) before effectively becoming the reboot for the setting and turning into Source this, Void that. The second game's Eternals were orignally the Raanaar from Beyond Divinity according to some concept art, and Damian was likely intended to be the disguised antagonist, actually making it a direct tie-in between BD and Divinity 2 instead of being half that and half a direct sequel to D:OS1. Despite all that, I loved all three of those (Dragon Commander too, despite its shortcomings), but BG3 teeters on the edge of being the equivalent of DA: Inquisition for me as far as the studio's one overhyped but ultimately underdelivering outing goes.
BG3's just the latest in the line, and I imagine decentralized writing didn't help matters much. Before Larian's writing could be hammy and awkward, but at least it was genuine and didn't take itself too seriously. It had a Pratchett-esque quality to it with an overall humorous setting with an occassional heavy theme (albeit handled with a lot less finesse and depth than Pratchett). BG3 is a mess that is now being retroactively explained as allegorical / "always intended as such", with headscratchers like Halsin making it all seem like a melting pot which nobody really cared to bring up to a standard of some kind.
