I do think the pendulum swung towards less favorable news about Diana after she died precisely because it was so hard for someone critical of Diana to get heard when she was alive. I heard some critical comments about Diana when she was alive and they sounded reasonable but they received the utmost contempt and scorn when she was alive.
There were a lot of people whom the world simply refused to hear when Diana was alive who finally got heard when she was dead.
Plus this, I think: (from the inquest transcripts: Q: coroner, A: Richard Kay)
Q. Generally speaking, was the Daily Mail a newspaper that
4 was fairly supportive of her and her position?
5 A. It was. It found in Diana someone with whom our readers
6 identified and we were therefore quite supportive of
7 her.
End of quote.
Someone with whom the readers identified. I think the way she lived the last month of her life and the way she died made absolutely clear, that she was
not someone with whom one could identify. As soon as the media realised that, their tune changed.
There had been a similar change after the first glitter had worn off the newly wed princess and Diana reacted to it by allowing the media to come closer to her, by allowing the media to turn her into a person people could identify with. Only after her death it turned out that she wasn't as approachable and as normal as she appeared to be. Another quote by Kay (same source) about the Diana-Simone Simmons relationship and the end of it:
Q. What, then, were Diana's views on this particular woman?
A. I think her relationship, in her view, had reached its
natural course and she no longer welcomed her interest
in her life.
Q.Did she express any other views that she had?
A. She just did not want to speak to her again.
End of quote.
Before we had heared that Diana used to phone Simmons for hours at night and suddenly, new phone number, no more interest, that was it. I think Diana through a behaviour like this, very regal indeed, had made herself quite some enemies and after her death she could not longer keep them in check with her charming personality.
Interestingly enough I doubt the RF was behind that move, they had done what they wanted right after the divorce, as Raine Spencer said at the inquest:
A. "I felt sorry for her [that is Diana]. I think she had
1 probably not realised that once she had divorced,
2 the Royal Family would shut her out. In addition to
3 this, her sister, Lady Jane Fellowes, had told her that
4 because of her husband's position, she could not see her
5 anymore and her brother Charles had withdrawn an offer
6 of a cottage on his estate because he did not want
7 the press intrusion that would result."
IMHO those who had come to know her simply waited after the divorce how her public image would turn out. Diana had made such terrible (and terribly stupid) mistakes while married, so one would have been right to wonder if it was possible for her to be more cautious in the future. But if she had been able to show that she could survive being just "Diana, princess of Wales" instead of HRH The Princess, I guess some doors would have opened up again. As it was, she made the mistake to trust Dodi and his driver and thus left the stage, leaving only her reputation - for the wolves.