Rust, by itself, isn't a panacea to add formal verification but one leg on the footstool of formal verification methodologies to produce safe(r/ish) software rather than subtly buggy software that's difficult to prove correct and more expensive to maintain.
"If it aint broke don't fix it" =~= "I've never gotten into an accident until now, so airbags and seatbelts are pointless." ==> reactive methodology / failure / hubris
We want to give up good things to get better things.
What is the vision for improving these tools with rust? What user benefit are they promising?
I’ve heard nothing but nebulous arguments about memory or security purity. There is no insight into how to do them better or faster; and in most cases they have demonstrated they didn’t even understand them fully to begin with, such as missing locales.
There isn’t even subjective value for users demanding it, it’s driven by rust developers.
From their README, they promise better error messages, extensions when relevant (example: --progress), and Linux, macOS, Windows and other platforms support. It is my understanding that the GnuWin32 coreutils were last updated in 2017 and had some subtle differences to regular GNU coreutils, so that's one set of users for whom there's clear benefit. Faster speed could be accomplished if architectural changes are viable, but for many of these tools they are IO-bound.
The fallacy here is that code is either "good code that works" or "bad code that needs to be rewritten". It doesn't work like that. "If it aint broke don't fix it" is actually terrible advice.