You know what's fun? Most of the characters you have wouldn't put in a game would be included if this game would be ever done, due to the fact, that they could sell the game easier with these
Plus some others too, like Captain America, Iron Man, Hulk, Thor. So characters, who had their own movies would totally make the cut for a game like this 
I know that those characters are sellers, and I feel that that is something unfortunate, because other cool characters with cool backgrounds and interesting powers would never get used. For instance in my list I included characters like secret, vixen, and legion. Those 3 I think are really unique but not really mentioned a whole lot. But I only learned about Legion from the episode in the x-men evolution series, and I first saw vixen in the JL:U series, and also secret was just featured on the young justice series, and all of them had something interesting about them, but they don't seem to get much attention.
I'm not much of a comic book person myself. I like watching the shows and movies because for me it is easy to find a start to end sequence, in the sense that you can start a show from episode 1 and finish with the last episode, and movies you watch the movie from start to finish, with comics I think that it would be hard to find a place to start, or even where to start since there are so many universes and many different lines that intersect with each other. So my knowledge comes from movies and shows, and from characters that I research using the internet, which to some may not be a sufficient amount of knowledge.
Also I find it interesting that in your list of others that would definitely be in the game (Ironman, Hulk, Capt. America, and Thor) were all male including the ones you said that I wouldn't put in that would be in all but 1 was male. In my list I included mostly a mixed gender, but many of the superhero games have mostly male heroes. In my opinion (keyword opinion) a lot of the women have better powers that I think would be more fun to play as.
I think though that DC incorporates males and females more equally than marvel (at least with featuring them) or maybe that's just what I think.
Also just to note my list consists of people I think would be fun to play as, I didn't include villians (exept when I talked about story line like raven's dad trigon, emma frost's past with the inner circle, and secret's brother Harm as a boss fight). I also didn't include NPC's either.