>>213885051He respected isildur and they were brothers in battle. You don't just kill someone like that, and if you did have fun going to war with humans and wiping out half of civilization in the process, even if you could beat humans easily Humans were a huge help in protecting middle earth and had been for a thousand years. You really wanna wipe them all out because one guy was a retard, who wasn't even himself and was being controlled by the real enemy?
Tldnr: It's complicated and about honor, you wouldn't understand