Monsters University (2013)
Frequently Asked Questions
The directors were aware of that line and tried out several scenes in which Sulley and Mike first met in grade school and then reunited in college. Everything they tried just distracted from the story they were trying to tell. On the advice of studio head John Lasseter, they dropped any attempt at explanation and hoped that viewers wouldn't remember the line or they would assume that Mike was speaking metaphorically ("you have been jealous of my good looks for a long time"). In a recent interview, the creators of Monsters University stated that "...since the fourth grade" is a typical phrase used by monsters. In this case, the joke would be that Mike is saying that Sulley has been jealous of his looks for a long time.
Probably because they cannot risk exposing the monster world to humans. The reason why they scare children is because it generates sufficient energy. When children tell their parents about seeing monsters in their bedroom, the parents simply attribute this to children's imagination. However, scaring adults with high frequency will lead to investigations of the phenomenon, which will almost certainly lead to the humans discovering the monster world. Sulley and Mike only did it because they had no choice; there was no other door back to Monsters University and staying in the human world any longer would only increase the risk of them getting caught. Also, if children are considered to be toxic and potentially dangerous, then adults (who are much faster and aggressive) would be considered an unacceptable bio-hazard.
Possibly because Crystal received more top billing than John Goodman.
Grammer was intending to voice Mr. Waternoose, but dropped out at the last minute. This forced the directors to write Mr. Waternoose out of the story and instead include him in a photo.