Ah I see. Well that hasn't been an issue for users for ages. Only a few important libraries are installed in the small root partition. Everyone will see it as 80/90% full, it's not a problem. All the programs you install from Cydia are now installed on the main partition. It makes NO difference how big the root partition is. That's only important for developers. And no you can't change the partition size, it's set at the iOS image creation. You'd need to create a custom firmware. But like I said, it's not important.