The early show represented Star as Nefcy created her in the beginning.
A representation of herself. A girl that didn't have too many friends, lived in a land of childish fantasy, a girl that didn't want to leave her 10-12 a time easier for her.
They could have continued that troop, to make the character actually grow...
To accept she can't do something as shitty as declare her 'love' in front of a class she only became part of for a year and expect the guy to leave the girl of his dreams for her.
To see what her ideal of 'grown up' meant, how Eclipsa would not care about consequences because she only thought about herself. So that she contemplated again if she wanted to 'not be like her mom' or if that was a bad idea.
To take responsabilities in her actions, realizing it was a mistake to give the crown (and the power it represented) to someone that had already thrown it away, and that once it has it back and gives it to the wrong people, the monsters turn eviler, in spite of 'good monsters' living between those evil ones.
Instead we got a girl who decides to commit genocide and forces two worlds together for selfish 'love'.