She was a foil to Amethyst, as an Earth gem who hated herself for her origins and succumbed to her self loathing instead of getting help and learning to accept herself.
She was a foil to Peridot, as a homeworld gem who Steven wasn't able to reach through to because she had too much baggage between the war, Rose, and being from Earth.
She was a foil to Lapis, as the half of Malachite who wanted to return to the fusion and wasn't able to move on or find healthier ways of coping with her trauma or past.
She introduced the force of Homeworld in The Return/Jailbreak (still the best season finale) and ended up showcasing how much damage the homeworld system can do to a gem, was also one of the biggest victims to Pink Diamond's actions which Steven felt guilty for
She was the only good antagonist to provide a lasting threat and stick to her ideals instead of being anticlimactically talk no jutsu'd unlike every fotm or the diamonds, she held up the middle of the show and kept things exciting while helping multiple characters get development and developing into an interesting character herself, which is why things immediately went to shit in s4 after she was shelved