I think it sounds better in your head than it would in reality. A story where the main villain, an irredeemable and inhuman curse wins in the end? Over the characters who we've watched grow, lose and get back up to fight? That's not good story-telling lol Sukuna has to lose in the end. Otherwise why are we even watching/reading? This isn't a story about the grim, malevolent world JJK is set in, its a story of humans fighting their own nature(curses). I usually like villains more than heroes but with Sukuna there isnt much to love, besides the drama he creates when he shows up. He crossed "the line of redemption" before the show even started, as stated by the many characters who tell of how he almost took over the world 1000 years ago. Maybe if we get backstory on him and see firsthand what he did to become the way he is presently I can begin to love the demon. But until then I'm patiently waiting for Gojo, Yuta, Megumi, Yuji or all combined to stomp him.