No, "Fury" should never have been written at all. Rewriting it would not have made that sick, morbid episode better.
Those in charge had two options: They could have come up with a good Kes come-back story or they could simply had left it as it was after "The Gift". Instead they did choose a third option in which the character was destroyed and humiliated. Adeliberate insult to the Kes fans.
If you want a good Kes come-back story, then read "Coming Home" on my Kes site.
As for Jennifer Lien's writing credits, the noble and benevolent people who came up with "Fury", this lovely gift to the Kes fans actually planned to kill of Kes in the episode. Jennifer had objections to that and made them change that. That's why she has writing credits for the episode.