Before you read all of this, understand that,
A) I loved this event. Loved it. I'm a gamer, love comic books, loved this event.
B) Even though I loved it, there was an issue with it in regards to characters participating in the event.
It's perfectly fine to question why things went the way that they did. TSTO hopefully is paying attention, reflecting on comments in the forum and their own decisions made. Gamergate can open positive discussion about women in gaming, role models, and the extreme negativity thrown at women when such topics are brought up (i.e., this thread...yikes, and this is in a family-friendly forum!)
They should know their audience by now - most are probably female, many would drop real $$ for a premium Lisa skin, this would have been an amazing time to release a MAGGIE character (Brainy Baby!!) - the forum would have exploded on that one!, and that we do pay attention and notice things that aren't there/left out/trivialized/overlooked/made indifferent. Or make us apologize or feel guilty for expressing what we are feeling or calling us "feminists.." Sorry, laughing at that one!
But yes, lack of female superheroes was noticed. And even if no new skins for Lisa were created, they could have simply had Marge throw fireballs, as bretro85 suggested, and Lisa fire arrows, having the Simpson family cluster together for this event as well as the other super heroes.