Sometimes you "realism" advocates slay me. You think the general public wouldn't buy bleached skin?
Did Pirates of the Caribbean 2: Dead Man's Chest scream "realistic" to you? And how much money did that movie make?
It's more about the tone that's already been established. Dead Man's Chest was a fantasy film, and while superhero films could be argued to be a fantasy subgenre, Begins, I'd say, falls somewhere between superhero film and crime film. A more "realistic" tone has been established.
I know, how realistic can you get when your protagonist dresses up as a giant bat to single-handedly beat up criminals? But there was a level of plausibility in the way it was presented. Of course there were "unrealistic" elements in the story - basically every film has unrealistic elements, even more sensible dramas. A story like Batman's is more fantastic, by nature.
But I'm sure most people would find it quite jarring if, in one of
these Batman films, an experiment caused a character to become half-man, half bat - that sounds more like something from the
more fantastic and tongue-in-cheek Spider-Man movies. In keeping with the tone established in the first film, the more fantastic elements from the comic books would simply not fit.
As for The Joker, whom this thread is obviously about, I don't think bleached skin would cross that threshold of being "too unrealistic" for inclusion in these movies. But there are reasons for his wearing make-up in this film, even though we may not fully realise them until we see the film. The way The Joker is presented in terms of his history, or lack thereof, may be one of these reasons. The fact that he has a cut smile and paints his face certainly raises questions, but a more fantastic deformity, like bleached skin, would
demand an explanation. But Nolan doesn't want to give us such an explanation. He wants The Joker to be more of a mystery, which is refreshing given the current trend toward excessive backstory (Hannibal Rising, to name an example). I think Nolan's been quoted as calling him "a force of nature", or something along those lines, a creature that cannot be understood.
And so, the decision to have The Joker wear make-up in this film, I believe, has more reason than simply, "bleached skin is too unrealistic". However, I would say that there are
some characters, story arcs, etc. which
would be too unrealistic to comfortably fit into the universe they've established with these films.
That was a pretty long post. Goodnight, folks.