After discussing this with someone, I've kind of come to a realization. The Diamonds are pretty crappy villains. The show wants us to understand the evils the gem species has committed against the universe, but at the same time wants us to feel bad for them for some emotional moment where everyone turns good in the end. I made up my own little idea to potentially fix that. Do feel free to put your own opinion as well, whether you like the idea or not.
The Gem species have shown themselves to be rather uncaring and ruthless to other forms of life. They harvest and turn other planets into their own, resulting in the genocide of possibly hundreds of alien species to expand their empire. The reason for this would be White Diamond. The first gem to achieve what she deems "perfection," she wishes to gift her species the same life she has and plans to ascend the gem race into godhood, her own perceived godhood. To do this, White has told her empire that the universe only belongs to them and that all other species are inferior to them. Filth that deserves to be culled in the name of perfection. Thus sparks the empires genocidal campaign.
Yellow Diamond would be by her side, as she would be closest to White in this idea. Blue, however, is not in the same mindset as them. Blue believes that all life in the universe holds as much value as their own. This way of thinking has caught her in trouble and even put against Yellow. This makes Blue the most morally correct Diamond, but cannot do much due to how much power the others hold.
Cut to when Steven and the others meet them. White plans on brainwashing Steven to make him Pink again, claiming that Steven is "tainted" by imperfection. Luckily the Crystal Gems save him from this, as well as other characters who have formed a resistance against White. Who's the leader you may ask? Blue herself, who stands up to White and Yellow. Yellow calls Blue a traitor, but White takes the battle. The group turning to Obsidian, they take Blues side as they take on the godly gem. They obviously get wrecked and Blue is about to be killed by White, but suddenly, Yellow attacks White to protect Blue. Seeing her friend, her sister, get beaten down by her broke her and saw just how much of a monster White truly is. In a last effort to defend Blue, Yellow takes on White but is ultimately defeated, her gem shattering and killing her.
Now I'm not sure how they would defeat her, but let's say Steven is able to use the pink rage form and is able to overpower White. Steven is hesitant, being the pacifist he is, and doesn't want to kill White. But he is persuaded that even though some people deserve redemption, some are too far gone. White has caused the deaths of millions, if not billions of lives across the Galaxy in her deranged idea of a utopia for her species. With a regretful and heavy heart, Steven shatters White and ends the tyrants reign.
After the battle, Blue takes the mantle of leader for the species and ends the original series on a solum note. Would Blue be able to redeem her species or would it eventually collapse with gems refusing to work under her? Only time would tell....
Oh yeah and Pink is still an asshole.
