I have to point out that Solasta, another game based in 5e, implemented in the kickstarter demo the usual reactions in the enemy´s turn.
In the video the dev made it clear that they don't believe that implimenting pop-up window works as well as it does in table-top.
He brought an interesting thing - they want unique animations for each reaction: which makes sense. D:OS biggest strength was externalising mechanics into the map visually, and it is a good think that they want to achieve the same with BG3 (express gameplay on screen, rather then via log). And you can't play the right animation, if player makes decision on what this animation was after it plays out, no?
At the end he also mentions that they are looking into ways of giving players precise controls over those limited reactions. So, as I suspected, they are very well aware of issues the change to the system creates.
