> I fail to see what advantage rewriting existing and proven tools with a new language would bring.
This is not the first rewrite, and won't be the last one. Earlier environments were very memory-constrained, which led to optimizing for memory usage; a rewrite with less memory constraints can focus on speed (as mentioned in the GNU coding standards: "For example, Unix utilities were generally optimized to minimize memory use; if you go for speed instead, your program will be very different. [...]").
The current challenge is the "end of Moore's law" leading to an increasing use of multiple cores, instead of faster cores. Developers will have to focus on parallelism instead of raw speed, and new languages can help.
> Shouldn't the main value new tools bring to be enable writing of new things?
Or writing old things in a new way.
> Isn't focusing on existing utils more like a lack of imagination and OCD on optimizing a thing beyond any further value?
These tools are the base over which your system is built (their GNU version isn't named "coreutils" for nothing). Focusing more effort on them makes sense.
> The current challenge is the "end of Moore's law" leading to an increasing use of multiple cores, instead of faster cores. Developers will have to focus on parallelism instead of raw speed, and new languages can help.
Moore's law is indeed nearing its end, but this also ends the multiple core trend.
If you're betting on multiple CPU cores taking off more than they did already, don't.
This is not the first rewrite, and won't be the last one. Earlier environments were very memory-constrained, which led to optimizing for memory usage; a rewrite with less memory constraints can focus on speed (as mentioned in the GNU coding standards: "For example, Unix utilities were generally optimized to minimize memory use; if you go for speed instead, your program will be very different. [...]").
The current challenge is the "end of Moore's law" leading to an increasing use of multiple cores, instead of faster cores. Developers will have to focus on parallelism instead of raw speed, and new languages can help.
> Shouldn't the main value new tools bring to be enable writing of new things?
Or writing old things in a new way.
> Isn't focusing on existing utils more like a lack of imagination and OCD on optimizing a thing beyond any further value?
These tools are the base over which your system is built (their GNU version isn't named "coreutils" for nothing). Focusing more effort on them makes sense.