[Girl Drink Drunk]

I think Bale intentionally played Bruce as a spoiled, rich asshole to give him this facade to hide behind. Bruce has been like this in the comics at times, probably to keep people from getting any hints that he is Batman. Considering he is goes around fighting crime in a tank-like vehicle, and using hightech armor and gadgets that cost a fortune, people might start to wise up if he displayed the same intelligence and brooding demeanor as Batman in the office. It's kind of like the differences in character between Clark Kent and his alter-ego.