Why? Because we want the reader to BECOME the character. The wonder and beauty of written fiction is it is the only medium in which a human being can become someone else. But it can't happen without empathy. Empathy is the identification, understanding and often sharing of, someone else's feelings and/or motives. I would even go so far as to say readers should have empathy for 99% of characters--that's what keeps us reading. The one exception is a particularly fascinating antagonist/villain, such as a Hannibal Lecter.
Of course, authors have many tools at their disposal to tell their stories and engender empathy. These include dialogue, character's thoughts, description of setting and action and narrative. There are some special writerly mechanisms to make characters empathetic:
- make the character an underdog or experience some kind of trauma
Note: it's important the character not feel sorry for him/herself
- show the character caring about other people
- show other people caring about the character
- have the character protect or help someone less powerful than themselves.
It has been said that the ability to create fiction and other artistic works is a fundamental aspect of human culture and one of the defining characteristics of humanity. So, why not use all the tools at your disposal to create fiction that engenders empathy and hence insights into the human condition?