Interesting. I didn't know that it improved so much during the project lifetime. Was it due to a few single changes or a bunch of tiny improvements moving the needle only in aggregate by that much?
A purely technical discussion on the problems that could down a Shuttle ignores the meta problem of poor risk analysis by the Shuttle managers. Basically they normalised deviance[0], in effect deciding that a technical problem wasn't an issue because they got away with it previously. This intrinsic weakness did not go away after the Challenger loss (hence Columbia [1]). Arguably, the only reason there wasn't another fatal loss was that the programme was grounded before after another accident could occur.
[0] https://en.wikipedia.org/wiki/Normalization_of_deviance
[1] https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...
We're seeing plenty of normalization of deviance with SLS and Orion though. There were the issues with various backup systems and IIRC no life support in Artemis 1, with issues with the heat shield only recently being made public, yet Artemis 2 is intended to carry a crew. So I would not be surprised if Congress only finally gives up on that waste when they cause another crew to be killed and can blame NASA instead of themselves.
Concorde was very loud and very fuel inefficient in an industry where efficiency is king, the modern struggle is not in achieving supersonic flight, but in doing it efficiently and quietly.
Similarly, the space shuttle was iconic, but more recent safety analyses have shown that it was a miracle only 2 launches resulted in total loss of crew, as initially it had a 1 in 9 chance of failure, later missions getting to 1 in 90. In comparison, all current human rated vehicles have to do better than 1 in 270. The Shuttle was also horrendously expensive, reusable in name only, and was limited heavily by requirements for it to be able to do certain things that it never actually ended up doing. Dreamchaser is supposed to be commercially viable, it can't burn billions per launch.
Similarly, with going to the Moon. We want to do more than just an Apollo style moonshot and establish a sustainable long term presence there (well, NASA wants to do more than that, Congress seems to just want to give money to Boeing), so now we have to make giant, spacious sci-fi-esque landers/bases that refuel in orbit before heading off.