I think you need to rewatch “Fury” if you think that’s how it ended, because they absolutely do revert Kes back to her old self in the end, making her remember that the crew of the Voyager were actually her friends and that they only ever helped her. It ends with Janeway offering her to stay on the ship, but she refuses and flies off to the Ocampa homeworld instead, having one last warm goodbye with Neelix in the transporter room.
No-one has to like “Fury” and it’s certainly not my favorite episode, but lets not misrepresent what actually happens in it. I don’t see the character assassination that some claim the episode is guilty of. And I don’t think I ever really understood what’s supposedly so incredibly bad about “Fury”. It’s not particularly special, but it’s a perfectly entertaining hour of Voyager. The whole concept of time traveling back to the beginning of the show is pretty cool and I would argue that Kes suffering from some form of Ocampan dementia is interesting, even if admittedly not realized to my full satisfaction.
I’ve worked with old people suffering from dementia and it’s absolutely a condition that can completely change someone’s character and behavior. It’s particularly hard for the family members of that person who have to witness this change and that person disappearing, So if anything, having Kes go through some version of that is actually pretty apt and sorry, I just can’t view the episode as all bad because of that.
If anything, the episode is when they finally deliver on the original premise of a character with such a limited lifespan. When they thought up the premise for Kes the idea was to show how someone like that would go through all stages of life in the span of the show’s run. Having written out the character in “The Gift” they avoided ever having to show Kes getting really old and suffering from what that entails. “Fury” at least gives us something to make true on the premise.
