Not all characters need to be "good" (not even the protagonist). Writing is a reflection of our world and our imagination and as such the characters will not always wear "white hats". I will take this article one step further and it is also my opinion that in terms of character development, ALL characters have elements of good and bad. To portray the "good character" as the beacon of kindness and generousity or the "bad character" as being completely evil with no redeeming characteristics are the types of characters that do not appeal to me. Every person has elements of good and bad, and in order to write a believable character and engaging character, I need to keep this in mind in terms of character development.
Along the very same lines, with my debut (but very much "in-progress") novel Pieces of Silver, I've made it my mandate to write the antagonist in such a manner that while he is altogether and evil and nasty fellow, that the reader will hopefully have a little empathy for him and see that does have redeeming qualities.