The main reason for this is the bad to worse batman movies of the past. Those movies and the TV series did major damage to the perception of Batman and the world he dwells in.bro-think its a superhero movie.not realistic type.its fantasy of course .
i personally never cn such movie like this one dark and deep.except porn![]()
Batman is not a squeaky clean good guy. He has his flaws. The old movies & TV series didnt show those.
Chris Nolan did the world a favor by sticking to the original Batman character in the comics to make his movies rather than the old movies and the TV series and thats why both Batman Begins and Dark Knight are so great. As the comics explored all these traits.
The moral issues that are prominent in the original comics are shown quite well in Dark Knight, thats why it was rated well.
BTW, watch Batman Under the Red Hood. It terms on the human side of the characters, its far better than Dark Knight.
not in the excellent category though 
quite different movies but both had some raw quality.