Okay,before we get into to this,I want to say that yeah,I did say that the movie could've been better if Elsa had mais screen time,but over-time opinions have changed.So,let's get into it shall we:
Now,I can understand this,Elsa is a wonderful character,but there are couple reasons why the scenes she had are what had to be.

The first is the development in the story.I don't know if using GCI allowed faster development time than hand drawn films,but this film had barely two years of proper development(Tangled had six,although much of it was to get the CGI good as it is),and even later before they solidified the characters.Keep in mind the Elsa was going to be the villain until late in the game.
So it's not very likely that they had much time to flesh out Elsa's story any further,when they didn't even know what Elsa is going to be for much of it.Elsa ans Anna being sisters was a late addition.
The segundo reason is less is more.The fact that Elsa has left many fans,myself included,wanting even mais of her,does show how well the character was done.But would it have worked as well in this specific story? I'm not sure?
What drove Elsa's character into anxiety and depression over her worry that her powers will harm others.And let me tell you,as someone who's suffering a bit from depression,focusing too much on that will only depress the story.Other filmes that focus on depression work much better por not focusing from just that(like the film Ordinary People,which was about the family instead of just the surviving brother).
Now you could say that there could be mais focus on her when she feels free from her old life.That would depend on what was showed.If it was just her playing around enjoying her new life,that would of course would just be padding.It could have worked if it showed hints of her looking back,but knowing that couldn't be,but that does get established in the film when Anna meets her at the ice castle.
Again,it's less being more.
If there was anything that could've been fleshed out more,I think it should have been better foreshadowed what happened right after the climax,which felt kind of rushed to me.But again,considering the scramble try to make the story as relatable as it is,I can live with that.
Besides,just like in the early 3D Sonic games where Shadow the Hedgehog got his own game due to his popularity,maybe in the upcoming sequel they'll make Elsa the focus this time(but if they give Elsa a amor interest,that would RUIN the movie for me).
Now many have claimed(including myself)that Elsa should have gotten mais scenes because Anna isn't a good protagonist due to being stupid.[b]That is utter bullsh*t.
I hope you guys enjoyed my artigo and leave your thoughts about in the comment section bellow,I don't really rely on others opinions,but it would be nice to see what you guys think.
As always,Smell ya' later!