The difficulty in making a Superman game is 2 fold.
1. Easy to pick up, intuitive, and satisfying flight controls. 2. How to design a story and game without taking away or limiting Superman's powers that still makes sense, is interesting, and fun to play, which means Superman can't be the god among mortals he is to most of the world and even most of the galaxy. Because Superman is less of a character you root for because he's physically tested in overcoming his opponents, and more of a symbol of perfection to be admired.
In my opinion, the most interesting Superman stories are the ones where Superman's powers are limited, or lost, however, nobody wants to play a game where you don't have full access to Superman's powers, because that would also feel pointless, why play a Superman game where you can't fully use his powers?
Just give it to Rocksteady and any of those problems are solved. ---