Plot

You may say I am merely criticizing without any constructive suggestion.

Em... If I were writing the story, it might go like this:

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The King of Arendelle has two daughters. Elsa, the elder one, has the special power of manipulating cold and ice at her own wish, while Anna, the young one, is just a lovely ordinary girl.

When the King gets old, he has great hope on Elsa and makes her to become the Queen of the country. Everyone is excited because they all think, with the special power of Elsa, their country will prosper. But, the reality is, after a short honeymoon period, they realize that their new Queen has difficulty to control her power. She looks down upon her ministers because she considers them useless people with no special capability. She takes whatever she wants from Dukes and sovereigns around and does not treat her alliance with fair terms. Soon afterwards, the country gradually gets frozen. Elsa is taken as a monster and has to exiled to an icy ivory tower.

After Elsa is forced to leave the country, Anna becomes the Queen of Arendelle. To begin with, she hesitates, because, without any special power like her elder sister, she doesn't think she could rule the country well. However, since the old King has no other children, she has to agree with reluctance.

I suppose you could imagine how the story is going to unfold subsequently?