I've gone on record that I am far from a Larian fan. My opinion on their work is midling at best. I don't really think that D/N cycle is all that important in practice. I've never really noticed it in the games I've played that had it and I don't really notice the lack of it in BG3. But I will say that on the point of principle, Larian is clearly trying to push things forward in several ways, in terms of reactivity and the interaction of systems, it feels like a failure of ambition that they didn't try to include a cycle and make use of that. On the other hand, could it be a matter of scope? One thing you have to hand to Larian, they do like to go big when it comes to what their systems can do. Maybe they looked at all the stuff they would have had to do to make the cycle feel 'worth it', i.e; npc schedules, dialogue, background chatter, items that interact with it, an internal clock connected to spell duration, etc, and decided it wouldn't be worth the increased scope.
