I had the same reaction to the ring. I think those boys revered their mother. She was, perhaps, the quintessential woman in their eyes. I interpret it as saying, "Here's a piece of my mother that I want you to have," rather than "Here's a piece of my parents' marriage."
Kate seems very comfortable in her skin, something Diana never had. I hope my impression is correct. As much as I'd love my children to live a fairy tale life, I don't think I'd want my daughters marrying into the royal family. However, I appreciate that William acknowledges the challenges his bride and her family will face. I heard him say in an interview that one of the reasons he waited was to make sure they were comfortable with the demands of royalty, or the demands of being related to royalty.
Sigh. Count me as one of those young girls who was glued to the TV for Charles and Diana's wedding. Diana died a few days after my first daughter was born, and I spent many sleepless hours holding a baby while watching the funeral activities and television specials. I think her ultimate goal was to see her children happy, and I hope that comes true.