And another thing, nobody gives a fuck about Wonder Woman either. The only reason she matters at all is for the sake of the Justice League not being a sausage fest.
Been watching some stuff on this game and I'm a bit shocked they positioned Wonder Woman as the narrative guide. Batman is the one the players actually know and have been playing as, so why would you A) Not make him the main narrative pull; and/or B) Not have him be the last bad guy? For example, in the series it's actually Batman himself that has all the plans and devices to 'kill' the Justice League. In the game, they just steal some of his plans and that's it. I would've instead made him a primary facet of defeating the Justice League, not only to keep him in the picture, but also to take some stress off of the suspension of disbelief when it comes to these goons killing any of these superheroes. Then, of course, at the end, you could have Batman be turned and knock him off, too. If anything, I'd have his ending be a sacrifice, like he gives himself up to Brainiac so as to reveal where he is or to get his defensive codes or whatever MacGuffin is needed to fulfill the title and of course push the squad itself into the end game.