Swen commented on this in a video from a day or two ago. Relevant part starts at 29:24:

https://www.twitch.tv/videos/763351879

30:03 - "There's much more tactical depth that we are able to put in there, that we wouldn't have been able to do in real-time-with-pause."

30:30 - "Actions, bonus actions, movement, manipulation of your actions, manipulation of your bonus actions, getting an extra action - all these things are lost when you make it real time."