Much as games have gotten better at delivering well-told stories, immaculate Hollywood-aping feats of acting and eye-popping visuals, there truly is an art to an effective plot twist.
Too crowbarred in and it feels last minute - some resurrected character or "it was all a dream!"-type revelation only raising eyebrows and deflating immersion. TOO fundamental without sticking the landing though, and it serves to undermine the entire project's most meaningful moments.
As with many stories and sagas that get added to or otherwise unfold across multiple instalments, there's rarely a detailed plan going in. Yes, depending on the scale of production, many plot markers may need to be hit, but there's plenty room for improvisation. This opens the door for marketing whims and cherrypicked plot points to be the thing an entire game is hung on. Marketing budgets inflate and the hype train is boarded by millions, all now waiting for that one immaculate reveal or piece of information that on the creative side, was never going to truly satisfy.
In fairness, there are exponentially more phenomenal stories in gaming than those that don't land, but when we've been lead to expect one thing and it's a total whiff? Us gamers aren't shy about letting everyone know about it.