Maybe it's not, in the end, the virtues of others that so wrenches our hearts as it is the sense of almost unbearably poignant recognition when we see them at their most base, in their sorrow and gluttony and foolishness. You need the virtues, too--some sort of virtues--but we don't care about Emma Bovary or Anna Karenina or Raskolnikov because they're good. We care about them because they're not admirable, because they're us, and because great writers have forgiven them for it.