Former ACME QA Tester.
IIRC Jean dying was an editorial decision.I heartily agree with that (bolding mine). I cut the comics some slack, since one could argue that they had written themselves into a corner with the character, and so maybe the only way she could be redeemed was through her death. The movie wouldn't had that excuse, since the got to write the whole plot out before filming started, so I'm glad they chose a more "empowered" arc for her.
In Claremont first draft Jean survived.