You know how a GL game would work? If they managed to limit the gameplay on PURPOSE. Imagine a KOTOR-like RPG, with the Corps as party members, being able to use different constructs as skills and willpower upgrades (or maybe even equippable rings of different colors) with energy charge being chosen in stats menus. You choose to have this much ring energy to charge your shields, this much to fight, this much to fly... Imagine facing Manhunters as main enemies, being able to fly as a method of transportation and dislocation without having it be an action-based gameplay. An action-based GL wouldn't work at all, unless they had him just shooting little beams out of his ring. If he was grounded, maybe they could work in some combos with several different kinds of constructs, but flying, PLUS different constructs? No. Although to be honest, it'd be perfect to have those end-of-bossfight QTE sequences where you press a few buttons and make some awesome huge constructs appear to finish off the enemies.
A truly good Green Lantern game would be something VERY tough to make. Heck, if it had to be action, without limiting the gameplay, I daresay it'd be tougher to make than a Superman game. Which is already something VERY hard to make due to the versatibility of the hero, in my opinion.