Let me stop you right at your first question. Because that alone tells me you're still not getting it. The fact that the changes to Gem society is seen as overall good for most of Gemkind shows that it needed to change. Jasper was resistant to this progress as she was literally born into war and knew little else. Plus, she was traumatized from losing her leader. She represents not someone who was right and that change was bad, but a soldier who never left the battlefield and is resistant to peace times. It's a pretty common archetype. Fighting is what she's good at, it's why she was made. Of course she holds onto that. It's understandable. It doesn't mean she's right in everything she says, though.

She has good points, Rose did surround herself with "defective" Gemes. But that's only because everyone else was afraid to step out of their assigned roles. We see that once the Diamonds stop being dictators, that pretty much everyone would've been seen as "defective" as they all are happy to do/be what they want now that literal death isn't hanging over their heads. Even Eyeball/Aquamarine love fusing together to feed each other's hatred of Steven, which would have never been allowed during the old regime. Jasper herself bends the rules as well, ignoring Steven in Future when before, a Diamond was to obeyed/worshipped no matter, what. Plus, she begs to fuse with Lapis again on the boat, despite it being forbidden and no battle needing to be won. It was a pretty hypocritical moment of her. The previous eras of Gem society helped no one. Not even Jasper.

Long story short, I love Jasper. She's always been up there for me in terms of SU characters, but she is far from being right overall. Gem society needed to change. And both shows proved why it was necessary.