In the movie industry, special effects and computer-generated imagery are becoming better and more realistic. As they'd improve, you'd expect moviegoers to more readily accept virtual worlds and characters, but that's not always the case. It turns out that people are incredibly put off by images or animations of humans that strive for realism, but aren't quite there yet.
A character like Wall-E is lovable because he's clearly not human but has many human-like qualities and expressions. In contrast, the more realistic CG-characters of Beowulf or The Polar Express are far closer to reality but somehow less appealing because of they haven't tripped the finish line. This phenomenon is called the "uncanny valley" - it's the point where, just before robots or animations look completely real, they trigger revulsion because they almost look human but are just off in subtle but important ways.
