People can play down Diana all they want, but she was big. She developed almost an iconic stature, especially with her death at such a young age. And this is why her memory resonates. Watching her sons grow up and reported on at every turn does a lot to keep her alive as well.
For some though, being 20 years out from her death now might have the same impact that we saw with the 9/11 phenomenon....everyone being patriotic and supportive in the years that ensued after, but now that we're further from it, it's just a fleeting memory for many and people are back to being nasty to each other at every turn. Memories fade real quickly in this country, and in this generation.
As for the musical though, I saw it in La Jolla and thought it was just okay. It was entertaining. But I always thought her life needed a bigger treatment. More like a rock opera type of treatment. Or a musical told in the manner of Evita. Sung from start to finish. Her iconic stature would fit that model better, imo, than the simple musical it is. I think the Lifetime analogy was a good one.