Um... Kristine Sutherland knew of her demise by the end of the third season; she had been planning to travel Europe, which is why she was absent for the majority of the fourth season. And then Joss' mother's death is what pushed for the exit in the fifth season, which was intended to change "Buffy, affecting her season’s dynamic with her priorities on family and the realization she can’t kill everything that could harm the ones she loves." It was never Sutherland's decision to die. She simply wanted to travel.
And Emma Caulfield admitted in one interview she requested to be killed off, because she didn't want to come back should Buffy continue into an eighth season, despite the overall knowing that it was unlikely to happen.
This. It's in the season 5 dvd extras Kristen Sutherland says "but you'll be back by season 5 right because I'm going to kill you"
There was nothing more to do with the character of Joyce and killing her forced buffy to grow up. It was brutal and epic.
The only two characters I'll say died needlessly are Cordelia (totally fine with making her the villain in season 4 but after Jasmine was born Cordy should have came back, the show wasn't the same without her bright sassy perky light and it was just a horrible way to kill off an og.
The second is Fred, such a weird thing to do. I feel like they should have had Fred be able to fight through Illyria like Ben with Glory.
Joyce and Tara's deaths added to the plot.
There wasn't much more to do with those characters and everyone forgets Doyle died cos Doyle died IRL.
I wish Weasley was killed though NGL