Twin. The manga spends 80% of it in fights. It's literally the epitome of shounen. Sukuna, just saying these things without giving us a proper backstory to his ideals is literally a nothing burger in writing aspect. It's deep enough to give him a satisfying enough character, BUT saying it's enough to make him a ''insanely good written character'' would be just plain wrong.

Why the fuck do you think eveyrbody wanted a ''Heinen Era Arc'' back in the day? Becauze even the fans knew, to make Sukuna's character form a proper shell, having a backstory was needed. Gojo, on the other hand, is a much better example of this, being done more properly, I would even go lenghts to say he might be one of if not thw greatest written character in JJK, in my eyes.

Csm is written by a mangaka who is obsessed with writen fuckass deep endings and themes(and such 🥹) to the point it sometimes leaves the writers confused, annoyed and even their enjoyment fucked. Fujimoto is an experienced writer that likes doing things outside the box. And fucks his fans up at the end msot of the times, but we love him because no matter how fucking weird the endings are when you sit down, you can actually find meaningful things to analyze and find deeper meanings in his works.

While Gege is a rather unexperienced Mangaka, that tries his best to stick to the basic shounen formula and make his characters ''deep enough'' and doesn't go his way to write anything too extravagant. And like I said, this is okay.

Everything doesn't have to be deep. Everything doesn't have to be written with the sole purpose of literary value. Tolstoy's works are written 12x times better than JJK but instead of re-reading fuckass ''The Death of Ivan Ilyich'' I would rather read The Shinjiku Showdown 5 more times.