
OTOH, I would assert that whether Disney intended it that way or not, people have ascribed a meaning to that song that does not directly relate to the plot of the movie.
"Let it Go" has become fairly ubiquitous anthem over the years used to imply "life is too short - forgive, forget, move on". In my worldview, purposefully choosing to lay down hurts, slights and offences, whether real or imagined, is a legitimate strategy for peaceful co-existence and it does not necessarily require or result in purging your life of everybody and everything that has troubled you.