them having souls despite their belief to the contrary I think worked pretty well with the 'mindflayers think they'll live on as part of the elder brain after death, but it's all bs'. monstrously intelligent and powerful creatures that at the end of the day are mere unwitting servitors despite their egotism to even more powerful entities.
What does retconning it actually accomplish? The plot doesn't really make that much more sense with the retcon. The Dead three's big plot is already pretty shaky as is. Retconning Mindflayers to being soulless creates if anything makes more awkward, since the player can become one without a game over.
Heck, apparently vampires have souls now too, so Larian is just really inconsistent here,
