> I know for a fact that I couldn't get someone (...) to use something like that day to day
I know for a fact the opposite is true for me. A simple shell syntax with an amazing documentation is all it takes for people to write useful scripts.
I'm confident i can teach basic programming to a total newbie using a structured shell in a few minutes. Explaining quirks of conditionals and loops in usual shells is trickier: should i use "-eq" or "=" or "=="? why am i iterating over a non-matching globset? etc.
> why not just learn bash?
I have a love-hate relationship with bash. It's good, but full of inconsistencies, and writing reliable, fail-safe scripts is really hard. I much prefer a language in which i'm less productive, but doesn't take me hours of debugging every time i'm reaching an edge case.
Also, bash has very little embedded tooling, compared to nushell. In many cases, you have to learn more tools (languages) like awk, jq. In nushell, such features are built-in.
> being installed on almost every Linux/Unix system
Well, bash is definitely very portable. But at this game, nothing can beat a standard POSIX /bin/sh. Who knows? It may outlive us all :)