Generally agree, BUT ...
a) In 5e, terrain conditions like elevated ground can give Advantage, but it is a DM's call. So Larian is not really bending the rules here.
b) the percentage to hit is a nice feature / much easier to evaluate. At best, there could be an option to show the rolls over AC.
The game still uses di rolls to determine the hit. You can see this in game by clicking the tiny arrow on the bottom left. It shows your chance to hit in percentage, but you can see what the game actually rolled and verify it was indeed a di roll. I THINK it also shows enemy AC there, but I can't remember 100% if the AC is part of what it shows or not.