Animals as symbols for humanity

It is not a new idea to have talking animals as characters in literature. Animal Farm is probably the most famous example but there have been more than just this. With the rise of comics/graphic novels we see emotionally stirring and intricate portraits of humanity being played out. The events of Maus, Squarriors and others are undeniably political, emotional and social. Why would an author and artist use animals as the main subject of their works when most of the time the plot/meaning of the work revolves around human experience? Is this a way to distance readers from the action so they focus on the main plot points or is this a way to make readers pay closer attention?