"Yes and not because "they are done","
They are done. "ls" for example doesn't need to do anything new.
"Or may be because C++ isn't fun to work with "
Oh I'm sorry, I didn't realise the appropriate language choice was one that was "fun". I thought we were talking about adults here, not preschoolers.
"C++ has no traits"
Wrong.
"no thread safety"
Wrong.
" no built-in utf-8 strings"
Plenty of libraries do it.
"no proper macros"
Define proper macro. C had them, C++ has them + constexpr which you've probably never heard of because you clearly know squat about modern C++ and are using something you heard about C++ in the 90s to form your opinion.
"no immutability by default"
Wrong. FFS what do you think the "const" and "mutable" keywords are for??
" it is still inherently unsafe even without using the raw pointer"
Vague handwaving crap demonstrating you have no clue.
"Why not, it will be an interesting project and I can only welcome it"
Err , maybe because python isn't shipped by default in a lot of distros so writing your utils in it might not be the best idea. Also in long pipe chains kicking off an entire python interpreter for each command would be hideously inefficient.
But then I wouldn't expect you to understand, you're just a clueless kid who is going to have an encounter with IT reality one day that will come as a shock to you.