The only reason this keeps being brought up is because certain people who may not like Nolan's approach, point to Two-Face, or the fear toxin as examples of "fantastical elements." Which, to them, by extension, means that Joker could have been permawhite, Bane should be huge, Catwoman should have ears, blah blah blah.
While there are fantastical elements in each of these movies, there are certain rules too. There is a certain level of plausibility whether some of you want to admit it or not, that lends these films to different interpretations of characters, which is why they were successful in the first place. Because the approach was different. There's only one film left, after that, let's hang Batman from as many gargoyles as they can build. For Pete sakes it'll at least give people something new to start whining about...