I think it's fair to say that attacking or insinuating that gov't officials were corrupt or culpable in societal problems was taboo back in the day. It is, however, an interesting story for "Batman" to explore.
Pinguin could reveal to Batman that he's only allowed to exist, in large part, because of the corrupt Mayor and District Attorney. Bruce realizes that beat up thugs isn't the solution and so he "buys" the Mayor's office; everyone in Gotham despises him for, but he actually makes changes that improve Gotham. It could also be a redemption arc for Harvey Dent.
On the live-action TV show of "The Tick", the actor who plays Batmanuel (a Latin spoof on Batman) also plays the mayor of Gotham in Nolan's "The Dark Knight." Kinda an inside joke for comic fans.
If they told the truth, Aztec Batman's story arch would begin because his father was killed for serving human child meat to Cortez and his men. A journal kept by one of Cortez's men make that very clear.
I feel like the movie ended too soon. I wanted to see conquistadors execute those savages