Going back to the 'why do some people love her so much' question. I think part of it is that she is seen as somebody who has taken on the establishment. She essentially tried to take down a head of state because even while professing love for the late Queen, she still accused the institution (of which the Queen had been leader for almost 70 years and was thus inseparable from it) of racism and mental cruelty. For lots of people, watching the establishment and the UK be openly criticised by people who were in it is enjoyable and they support that.
I personally enjoy reading about her and Harry because of how controversial they are. I can genuinely see both sides and my views are nuanced although they veer towards being critical of them. It makes them interesting to think about, sort of my version of following a soap opera. I also think of MacBeth with the 'fatal flaw' - somebody who could have been a good leader but for his ambition.
E.g.
As above, she wants to take on the establishment...but she loves her title and wanted her children to be Prince/Princess.
I think she's a talented public speaker...if only what she said made more sense.
I think she does genuinely take an interest in social issues...if only she could resist trying to puff up her own consequence while doing that work.
I think she was brave and hardworking while pursuing her acting career...but the skills and personality traits that helped her succeed in that industry don't work so well outside of it (the hustling, which is not something British people like in the royals).
I think she has come in for a lot of criticism which would be better directed at Harry...but his massive personality shift when he met her means that she likely does have an outsize influence on him and it's hard to imagine him spectacularly betraying his family if he didn't have her.
I think that a lot of the criticism is because she's Californian/American...but then it was also unwise on her part to not try to understand better the culture she married into, especially given that she really did give up a lot to come over here.
I think if she had been ever-so-slightly different, she'd have made a great royal. And it's the 'so near but so far' thing along with all the other many discussion points which generates interest and criticism. And the more criticism there is, the more her supporters come to her defence.
I think PP are right that they are incredibly frustrated at her current public profile (and his!). I think their single biggest mistake in terms of general 'likeability' was that they should have been very clear about separating out the Royal Family, the press and the UK public. They should have lavished praise on the latter (like Diana's 'I want to be Queen of People's Hearts, in people's hearts' - she was saying that the public's affection for her meant something to her). It would have made a lot of difference if they had exonerated the British public. By not doing so, as PP have said, they genuinely did damage the UK's standing on an international stage, in a way that they wouldn't have done if they had reserved their anger for the RF and the press.