I just created a model from a table with over 20 columns. A few days ago I had to hardcode a list of settings I screenscraped into a JS array in the Chrome console. You can't refactor things like that.
When it's a text editing operation that you're trying to do (as opposed to a defined transformation on valid source) then it makes sense to use a text editor.
I keep emacs and intellij open usually.
But there is also column selection mode.