I think there was a bit of guilt mixed in with the hysteria tbh for the part people played in her demise through the constant consumption of newspaper articles and photos. And people of my generation (born at roughly the same time) had literally followed her life, from the time she became engaged to it's very end, so there was an expectation I suppose that she would live the usual three score years and ten and complete shock when she died so suddenly.
She was tall and naturally photogenic and the British tabloids and foreign media made huge amounts of money from her image. The press built her up in order to knock her down in more or less continuous cycle. I once saw a documentary clip of paparazzi swearing at her, spitting and calling her a whore, in order to get her to react so they would get a nice cash payout for an action photo! Truly vile!
Also it's hard to describe with so many high profile celebrities being so accessible nowadays through sm, but at that time she was one of the most famous women in the world who had a huge following among diverse sections of society; among gay men for one (because of her work with the Terrence Higgins Trust) and among many ethnic minorities groups and the homeless; and other groups with whom the royals were not traditionally that popular.
The palace machine in typically misogynistic style has done it's best to cast her as an unstable airhead for the past couple of decades, but her press secretary who worked with her for eight years said she was extremely disciplined, energetic and professional when it came to her charity work. She definitely had a natural warmth and an intuitive knack of interacting well with people; as anyone who has done any hospital visiting will tell you, it's not always an easy job. I don't think anyone regarded her as a saint, but in a way people responded to her flaws, and she was liked for her warmth and humour, and many felt genuine sadness when she died.