I think the premise of this could make for a helluva game. Playing as the bad guys is always more fun anyways.
The Arkham games were fun, but their attempts to pretend that Batman wasn't actually killing people with those utterly brutal takedowns were always ridiculous. The worst was the hilarious Batmobile levels against "robot cars".
Being a bunch of scumbag super-villains allows players to have fun while also getting to feature all the League as heroes using all their powers (many of which would be very difficult to translate into player controlled gameplay)