You keep repeating this, but you never explain what it means.
All you had to do was ask.
First, let's cut to the ends of the three films, and in each case there's a bit of dialogue that occurs when the philosophical differences between the hero reach an impass. In the first film, Ra's Al Ghul states that if anyone stands in the way of true justice, you simply walk up behind them and stab them in the back, while Bruce says that the people in the city are still worht saving. This is where the divide happens. In the second film, Joker says that everyone is or can be just as cruel and nasty as he is, if they are just given a push, while Bruce says that the city proved otherwise. In the last film, Bane says (cue awful Bane voice): "So you've come to die with your city???!!" To which, Batman responds: "Noooo.... I came to stop you!!!"
But let's go deeper. None of the films are perfect. However, the first film dealt with quite a few complicated themes such as the nature of fear, and whether vengeance is the same as justice. It had a teacher and student who agree on many things save for their way of going about it. The action might encompass an entire city, but the real battle was something that was very personal, and came down to a philosophical difference.
The second film dealt with the idea that things in the city were going to get worse before they got better. The film had many more stories and a complex narrative of events - but these things never eclipsed and actually enhanced a sense of paranoia that everyone felt through the whole film: everyone from the characters to the audience. It ran much deeper, stringing together what was at times a complex and what could be called a convoluted narrative. That much of what happened was unlikely in hindsight, this sense of a paranoia was heightened with every scene as the film went on, and the audience hadn't much like it before.
The narrative, meaning that all these stories and characters and interactions, was just as complex in the third film, but the story - the very basic foundation upon which they were built on - was very simple. There was no sense of paranoia that was felt equally by the audience and the characters. Instead, there's a lot of new characters, and a lot of chance meetings and contrivances so only the main characters meet up with other main characters so that plot points could all connect and resolve, and the viewer (when he or she is trying not to figure out what Bane is saying or what his motivations are) is wondering why everything is so needlessly convoluted.