Do you know what aliasing is in a game? When the edges are too sharp? They can look okay in a still image, but they are really noticeable when things are in motion. Another such example is the moire effect. Moire is very noticeable in still images too, but when moving, it's really noticeable.

These blur effects, like any other graphical thing, can have a similar effect when combined with motion. The animate function is to bring these issues out, if there is any.