The most effective way for us to sympathize and feel horrified with 9/11 is to individualize loss. We feel empathy and compassion for the little girl who lost her father.
But do we really notice the odd thousand of people gone? Are we afraid to feel grateful that there are less people crowding the streets, or standing in line for coffee or a movie? Perhaps built into our primitive impulses is a lack of empathy (or evil) for the loss of a great multitude because we know, deep down, we will have easier lives.
This has nothing to do with Batman.