Then what would happen afterwords? What would we do then? What would we strive and die for if not for something better? In a perfect world, its perfect yes... but its only an illusion. A still clear pond of water is beautiful at the moment of its inception after the storm has passed and the waters calm. But eventually it festers, stagnates and grows rotten.
If we finally achieved a perfect world, our fighting would finally be finished, and we could move on.
A perfect world would be of great worth because it's one we fought for.