I actually really like it as an aesthetic choice. It's possible that the roll itself might slow the pace of gameplay, but in principle seeing the dice roll on screen is a fun way to get players to connect with the game. I think it's a way of allowing a different kind of immersion, giving players the ability to feel the tension of waiting to see if the dice are in your favour. And to relate that to the primary topic, I think they should definitely show both rolls when you have dis/advantage.
