I remember 20 years ago how much Catherine was criticised in the press for being "too middle-class" for the royal family.
But I think their approach turned out to be the right one. They were very young when they met, only 19 or 20 and took things very slowly. I think William appreciated the Middleton family - their loyalty, not having a house full of staff who might sell stories (looking at you Paul Burrell), and the more relaxed lifestyle of cooking or spending time together. I remember one of those Channel 5 documentaries with the former Highgrove butler, Grant Harrold, who talked about the change in atmosphere when Catherine started coming to Highgrove... William and Catherine would come into the kitchen, sit on the units and chat with staff.
It's odd that Harry seems to be the opposite and actually seems to be recreating the upbringing he so roundly criticised for his own children - huge status house, live in staff, oppressive security, leaving the kids at home for weeks at a time...
I think it's also clear that the Middletons have had a positive influence on the Wales family. They are a much more hands-on and practical family. For example I struggle to imagine Charles babysitting or fixing a bike - but it's not a struggle to imagine Michael Middleton doing this. It's not an age thing as both grandads are currently 77. But Charles has always appeared much older than his years.
I think in decades to come, people will point to Catherine being the true moderniser of the royal family.