I get that. I'm just surprised it's still considered acceptable.

I feel like even simple JSON would be a better output. Sure, humans would have a problem reading it but that's what shells are for.

That JSON would be the text output of the command. There are utilities like grep, find, sed, awk, git porcelain, readlink, basedir, which, that write output suitable for machines on stdout and other utilities that write output suitable for humans.

If you want to be a good UNIX netizen then stdout is for machines while stderr is for humans.