I believe having the ammo and consumables on the UI and not in the inventory takes away from the tactility and inventory management, but will speed up game play and allow you to be more aware of your inventory in fire fights where checking your invintory may not be an option.
It would be great if they could somehow implement a way to have both HUDs in the game. Possibly depending on just a click in your settings page or even different game modes for the HUD. The more options the better
I actually like the current ui: It is simple an therefore realistic not like in other shooters where you get every piece of information. I mean e.g. you could abuse the displayed distance in meters in the hud to shoot better, cause you don't need to estimate the distance anymore.