What was too unrealistic about Nolans batman villians? Outside of Scarecrow they were all Gangsters or Terrorists. Maybe anarchist fits Joker better then terrorist, but thats not important.
When your starting point is a man wearing an elaborate Bat costume with pointy ears and all... Your bar for unrealistic is instantly raised. Anything short of Superhumans is in the ssme realm of realism. Clayface, Killer Croc, ManBat, and Grundy all surpass that bar. But characters like Bane, Scarecrow, Mad Hatter , and The Court of Owls aren't any crazier then Batman himself. Batman being by far the most absurd thing in the world doesn't have much legs imo. Theres needs to be a balance.