I am answering subjectively here, but I think it really comes down to evoking even more sympathy for the main characters. Not only do they often have to battle difficult circumstances (i.e. being an outcast or something similar), but they also have to deal with being alone in the world. All of this creates genuine sympathy for the protagonists.
This Daily Mail article also addressed the issue. Although they agreed with my first point, they also had this fascinating theory:
Might the death of Walt Disney's mother - and the lifelong guilt
this left her son with - be the catalyst for the death of parents in
In 1938 and riding high with the proceeds from his first big
screen movie Sleeping Beauty, Walt bought his mother, Flora, and his
father, Elias, a house in LA as a golden wedding anniversary present.
Within days of moving in, Flora complained about the stultifying
temperatures coming from the central heating boiler and her doting son
arranged for a swift replacement.
Days later, Flora died from
asphyxiation caused by the new, poorly-installed, boiler.
Disney's misplaced guilt over his mother's death have led him to
airbrush parents - mothers in particular - out of his works?
has that motivation, after his death in 1966, become a Disney
Certainly, it would explain the types of folk stories and
fairytales that Disney has acquired for adaptation, even when there
are numerous other traditional tales that feature a mother and father.
Finally, it's also worth noting that not all movies have dead parents. This list shows the following Disney films as having both parents alive at the end of the film:
- Lady and the Tramp
- Sleeping Beauty
- One Hundred and One Dalmatians
- The Incredibles
- Peter Pan
- Lion King 2
- Tangled (although parent-like villain dies)
I whipped this answer up fairly quickly and really should have expanded on a few points. As many comments under the post have indicated, this "style" is a common trope. As TV Tropes express (rather tongue-in-cheek):
Parents Are Useless. They leave you and abuse you. Good Parents are
hard to come by. It appears that the only decent parents are the dead
These are the parents that leave the characters behind, not by
choice, early on in the story, sometimes even before the story begins.
The characters are now all alone with no family. They may find a
Parental Substitute, but they may not always be the best guardians.
These often heroic characters will always have fond memories of their
parents. That's because these parents did everything right while they
were alive. They spent time with their children and taught them
invaluable life lessons that they continue to keep even to this day.
Even though the parents are gone now, the actions of the parents still
affect the character and keep him going.
Finally, it does make logical sense (from an animation point of view) for parents to die as it would most definitely cut down on production costs - although the life lessons learned from their deaths are obviously the main focus.