Animation simulates "real" action with action produced artificially from generated images or manipulated models. These images or models are "animated" by our mind (and eye!)'s tendency toward persistence of vision.
But what level of "real" action is being simulated by an animated film? Our perceptual experience of a scene takes place at many levels. At a very fine-grained level, we perceive colors, shapes, subtle movements and details. At a more coarse-grained level, we chunk our experience into concepts: a sly smile, a knowing look, a murder, a pimp mobile, etc.
Some people prize the successful animation of the fine-grained structure of the world very highly. In fact, we generally demand a successful reproduction of fine-grained experience if the animation is to be integrated with "actual" footage which already (by definition) exemplifies it (e.g. the dinosaurs in Jurassic Park (1993), Gollum in The Two Towers (2002), or the flora in Avatar (2009).
Some of us, however, prefer a more coarse-grained style of animation, found in, for example, South Park. The details of motion and texture are completely obscured in most South Park scenes (the animation is designed to imitate the properties of construction paper cut-outs, after all). This style of animation gains its communicative power from the representation and sequence of more coarse-grained tropes like the suggestive eyebrow, the power zoom, or the anchorman's hair. These tropes have emerged as part of the language of visual communication, honed and differentiated by decades of film and TV. From this palette, South Park is able to construct a subtle and complex sequence of animated signals.
Consider, for example, the moment in season 5, episode 13, when Cartman convinces Congress to legalize stem cell research through a heart felt speech and a spontaneous rendition of Asia's "Heat of the Moment." Cartman goes through the motions of a heart felt speech, with all the trimmings (heart-string-pulling background music, personal references, tears, etc.), then he breaks out into the "Heat of the Moment," his lone faltering voice echoing above the Congressmen. When the Congressmen join in, we are treated to a striking juxtaposition of a stereotypical display of feel-good mass expression (cheaply implemented in countless public forums: the spontaneous public dancing in Michael Jackson videos, the singing at the end of Scrooged, every musical ever made) and the irony and omen of manipulation brought to the act by Cartman's character. (Add to this the fact that Cartman's rendition is more sensitive and nuanced than the original . . . )
Another example can be found in Superstar: The Karen Carpenter Story, Todd Haynes' notorious bulimia bio pic. Most of the film recreates episodes from Karen's life with made up Barbie dolls on specially created sets. Although the details of characters' faces and movements lack expressive detail, the vocabulary of camera movement and cutting which viewers are familiar with from film and TV allows for the telling of a complex and subtle story.
Interestingly, in both South Park and Superstar, the visual language of cinema is employed with great ironic effect. The "message" movie or TV special is lampooned at the same time as an actual message is conveyed.