I guess it’s just a personal opinion, but I think that the 4KXX versions have much more than 720p of fine detail. There’s some stuff there, like the details on the Tantive 4 door frame, that haven’t been noticeable in any previous release. It isn’t as good as a restoration from the negative, but it’s definitely HD.
The Blu-ray definitely has some spots where color boosting clips the detail out of the image. Typically red lights, but you can occasionally see it elsewhere. And there’s a bit in Jedi where the film scanner was just out of focus for a few minutes (already fixed in DeEd). But seriously, these are exceptions to the rule. The Blu rays had more fine detail than a projection print, and the difference is still apparent scaled down to 720p. The UHD’s even moreso, in spite of being DNR’d into oblivion.