This implies the different approaches are like building a house with a safe and solid foundation, or patchworking a foundation with copious amounts of duct tape.
And in this vein, the C++ EWG prefers the duct tape approach... because laying new foundations in a well-regulated manner is hard, or rather, presents an "irreconcilable design disagreement...."
Taking a step back, the EWG (like all corporate programmers) are taking the path of least resistance ("what checks the box yet requires the least amount of effort, and has an off switch?").
No, what's happened is a choice. In your house metaphor, the house has already been built, and people have been living in it for years/decades/
The Rust proposal is like a change to the building code - to get the new benefits of the new code, you need to update everything - basically a major renovation. In the meantime, the people living in the house must live somewhere else until it's all fixed. They get the benefit of the new code (safety, security, etc), but it's a major inconvenience.
The proposal they went with is more like what happens today when the code changes - you have to build your new additions to the house to the new standard, but you don't have to renovate your entire house just because you wanted to enclose the patio.
C++ code has an extremely long lifetime, and it's undergone extremely big changes in the past 20 years. But the fact is you can still compile code from the late 90s using today's compilers is a huge thing. Other languages have had problems - Perl not so much, but most people don't see Perl as more than a temporary language - you write it one, then you write it off. But the Python 2 to 3 transition took way too long - Python 2 was deprecated at a time when Python 3 code was incompatible, and we're still dealing with the problem today where you're not sure "python" is 2 or 3, and there's still python2 code out there despite it being obsoleted at least a decade ago.
There's a lot of C++ code out there, likely way more of it is in maintenance mode than new C++ code written. Memory safety is a good ideal, but if you have to renovate the entire house to use it the vast majority of C++ code would choose not to use it over having to go through the entire code base to fix it up. Decades later that code will still not be up to spec because no one has the time/effort/money to fix up the code and only the new code will have the benefits.
And if you give anyone the thought of having to rewrite the codebase, that's where you get enshittification happening because why modify the existing application when you can start a new version from scratch that includes cloud, subscriptions and all sorts of stuff you couldn't easily do in the old code. You can abandon the old codebase and give everyone an upgrade to the new version.