Bad writing. Jane Foster is a great character.

Neither

Jane Foster and Odinson are the least of this films problems,

The Main Issues with this film is 1. How they wrote Gorr (and even him as a character isn't that bad when you don't compare him to his comic counterpart), the heavy focus on Humor Based characters, and how they Nerf Lady Sif's Character.

Yeah neither. She was great all around in her self contained arc here. Look forward to her hopefully being the next Valkyrie in the future.

She was good but I thin the story that had for her was wrong

She didn't needed to be killed off

Mighty Thor could have been written so she could be Thor's successor in case Chris decides to leave then Mighty Thor would have taken over

But now Thor doesn't really have a true successor yet

1. She was dying sooner or later due to her Cancer in her body, this is a fact.

2. Thor does have a successor, her name is Love.

1. The cancer story was the wrong choice

2. The better successor than Love would be Beta Ray Bill

My Man, Jane has always been a tragic character, the Cancer is her story. It's what make her different then Odinson and Beta. She's a character that doesn't stay as Thor but becomes a Valkyrie later on.

Beta Rey Bill is simply too old in the MCU to be the next Successor. It needed to be a younger character like Love.

My man they wasted Jane Foster for a story that probably could have been changed. Plus since Jane wasn’t popular this could have given a good story for her since for the first two movies she was just the love interest and then she was absent from Ragnarok

Love and Thunder would have been a good way to give her a proper story arc that doesn’t end killing her off

Beta Rat Bill would be a fun choice to have as Thor’s future replacement

1. Don't buy into the sexism grifter perspective on the narrative. Jane's story was liked on it's own level. Max level that was hated was Thor himself being seen as minimal in the same storyline.

2. That's not an excuse to not adapt said story faithfully. Especially for a universe people constantly complain they don't kill characters in.

3. Your option is essentially to have her tossed aside for a character they are just introducing to the audience instead of a slow buildup like with Love AKA Singularity. Along with removing Jane's heroic sacrifice.