didn't have the time to tell Isildur's whole story. In the books, Isildur does disregard Elrond's advice and keeps the Ring immediately after defeating Sauron, claiming it as compensation for the deaths of his father and brother, a Numenorean custom. But rather than corrupting him like in the film, he simply finds that he can't use it effectively and describes touching it as painful. He eventually realizes that the Ring cannot be used for good and that he needs to take the Ring to Elrond, who would no doubt destroy it. Isildur is on the way to Rivendell when he is attacked by orcs, summoned by the Ring. Isildur fights alongside his men, only fleeing when his son commands him to use the Ring and flee, since the battle was clearly lost. The Ring then betrays him precisely because it failed to corrupt Isildur. It was the only way to avoid its destruction. When In the moments after losing the Ring and before death, Tolkien describes Isildur as feeling the removal of a great burden and he is actually glad to lose it, unlike Gollum, Bilbo, and Frodo.

He gets the short end of the stick in the films because there just wasn't time and the film version works well, so I don't fault Jackson for the change. Rings of Power, however, does have the time. Hopefully they don't screw it up, but I'm not that optimistic.