Based off of the lyrics/purpose of Into the Unknown and Show Yourself (And frankly, I still think Some Things Never Change was supposed to get a reprise talking about how change isn't all bad), they just got Elsa's character arc wrong, but kept the payoff for it.
Elsa sings about how her powers are growing stronger and that she doesn't feel like she belongs in Arrendelle. So, the natural progression for that is that we actually see her struggling to both fit in in Arrendelle (not just game night with Anna, Kristoff, and Olaf) and to reign in her magic (maybe she's making things bigger than she wants, or it's creating details that she didn't intend) so she asks the question, "This doesn't feel right, am I meant for something more than this?"
Then during Show Yourself, you get the answer. "You have these powers because you ARE meant for something more, if you'll step into the light and get a new dress."
F2 main failure is not having a strong enough throughline for both sisters to wrap up the plot together. F1 is Anna's sacrifice to save Elsa that wins the day. F2 is just Elsa saving the day because murderhorse runs fast.
Honestly, I think it would have been better if SY was much later in the film, like after they resolve the big plot danger. Elsa gets a taste of what her life could be like if she chooses to become the fifth spirit, and she has to decide if she should go or stay with Anna.
I dunno, now I'm just rambling.