What makes Utsuro a fantastic antagonist is that he’s the culmination of the deterministic world view that is so central in Gintama. Utsuro never asked for the power of immortality but because of fear and jealousy he was persecuted by humanity for centuries.

The experience of persecution directly lead to him seeing his own power as a curse and humanity as something irredeemable. Utsuro and his plan to destroy Earth doesn’t come in a vacuum. He saw humanity make the same mistakes for centuries and that history gave him the

Assurance that his plan and goal was indeed correct. Utsuro wanted to move forward which is how the Shouyou personality came into being. Even then though he was dragged back into the role as the reaper whose only purpose is to kill. The final Utsuro personality then is the

Culmination of all the resentment and suffering he has faced. If they see him as nothing but as a reaper of death then he resolves he’ll become a reaper so powerful that even he will be able to die. It’s only in his final moments he realizes the fundamental lesson

Shouyou himself learned. Even if humanity stumbles it should still be given the opportunity to redeem itself. While he always desired death perhaps even more importantly he wanted to be reassured that humanity was capable of more than just hate.