We need heroes in our society, or in any society, because they give us someone to model ourselves after. The average human being, however pushed around or caged in they may be is unwilling to brave the dangers inherent to resolving the problems that plague them. Crime may overwhelm a city, but we do not care until it affects us personally; and even then we only usually worry about whatever facet of it has impact on our own life. We are inherently selfish creatures, and are possessed of a vile need to protect our own before, or even at the cost of, others.
However, in the image of a superhero we see somebody who is willing to sacrifice themselves in order to improve our lot. Whether this is a fictional superhero like Batman or Spiderman, or a real life hero such as a soldier who throws himself on a grenade to save those around him does not matter. What matters instead is that we are given role models that exemplify what we know we should morally do, but what we often cannot make ourselves do. We see somebody take the initiative and right the wrongs, despite the dangers to themselves.
A society without superheroes is a society without hope, where the human condition inflicts despair and misery alone. Without somebody, real or fiction, to model our behavior after, we will only continue to behave as selfishly as we can. Every religion is based on this ideal, from Christianity to Buddhism to Islam; we follow the example of someone who sacrificed him or herself for a greater cause, and in doing so we improve the lives of those around us. These religious heroes serve just as important a purpose of any other role model; they give us somebody to pattern ourselves after.
We have all had a role model at some point in our lives, and many of us still do. They are what we cling to when we face hardship or a difficult decision. They are the people we think of in dark times, and consider "What would Jesus, or Abe Lincoln, or Jackie Robinson, or even Superman do?” And the...