Avatar: The Last Airbender was too scared to show viewers these events that depict the Hundred Year War's brutality.
As Korra tried to fight Unalaq, Vaatu extracted Raava (the Avatar Spirit) from Korra. Raava was attacked, causing her to disappear. By losing her, Korra ended up severing her ties with her past lives, ...
Korra suffered a lot to be the Avatar, even more so than Aang – which made her a much realer & richer character.