Because I often want it to write and execute scripts in it's thinking loop in order to test assumptions or fetch data to come up with better solutions.
Can't it write `/tmp/test.sh` or `./test.sh` and execute it under my approach? This is what I've been doing as my status quo workflow with Codex, and I make sure I run Codex from a place where `.` happens to be a folder I'm okay with it messing up in.
That's how codex already works so you're not suggesting anything new, but it doesn't give write access at all of you set it to read only.
And when "it" is an arbitrary bash/python/javascript command, what then?