What I'd really love is something like Arma 2, but with a completely overhauled UI. The UI is, consistently, the thing that keeps me from really enjoying that game. There are menus on top of menus on top of menus to do something like order one of your troops to move to a specific point. I really believe that someone could look at all that stuff and streamline the entire thing without taking away from the ridiculous depth of that game. Unfortunately, from what few videos I've seen of the next game, Arma 3, it looks like the UI hasn't changed at all.
They tried to make the UI easier in Arma 2, but they did it by adding a (largely useless) new menu on top of the old one. And to make room for the new one, they hid the old one so you pretty much had to memorize the initial ten key-presses to use it. It was pretty much a disaster.
They say they are going to do something drastic with it in Arma 3. We will see I guess.