Thank you for sharing your experiences, OP. I have been complaining about the gradual ease in difficulty for the past year. I really want CBU3 to atleast impose stronger ilevel restrictions on capstone fights. It's true that Thordan was easy on release, but the others used to have a lot of bite to them. I remember Shinryu was a brick wall for many people and I had a blast queueing up for the fight just to help members of my Free Company get through. Similar things could be said of the other capstones at launch, though in my experience Shinryu was always the biggest hurdle.
I'm crossing my fingers that this major issue will be addressed during the upcoming Live Letter at TGS, but I don't want to hold my breath. Endwalker has only been out for a year and a half and is still considered to be "current content," and yet its capstone trial and the current Alliance raids are suffering from overkill far more than any previous expansion's. Along with the lack of proper ilevels synching, I imagine a large part of this is caused by the stat squish they implemented at Endwalker's release to make the game calculate numbers easier. The breakdown of content needs to be addressed sooner than later.