Python is my main language at this point. One of my uses is writing test scripts that may end up running on several computers that are both on- and off-network. So I walk up to a computer, install Python, maybe one or two modules, my program, hook up some hardware, and off we go. At my workplace, this is presently around a dozen computers.

There's a chance that I will need an editor: If a program crashes, needs to be changed, or I want to show somebody how to modify it themselves. Having something built-in with the nice colors, indents, and syntax checking, the same on every PC, is just plain handy. Otherwise, it wouldn't kill me to add a code editor to my collection of installers that I carry in my pocket, but it would be one more thing.

So I like the idea of a built in editor.

For beginners to learn. I started on it as it's super easy to run and debug on windows, which doesn't have a good terminal.

Windows has such piss poor command line support that it's the only reasonable way to use a python REPL. Outside of Windows I don't think it really has much of a use.

Personally I'd choose iPython notebooks over IDLE on any platform but IDLE comes with python by default so it's easier in some situations like teaching a class.

My answer: I have a cursor I can move to previous lines, copy-paste like I do in a code editor, and generally move around like I would in a code editor. My take is kind of the opposite: I don't believe we don't have these capabilities in other command lines.

For Windows, it's easier to start IDLE than it is to start python from a command line, and the editor is better. It's still terrible, but at least it's better.