It would be nice to have the option to swap between visual and text based editing for a document. Sometimes it’s difficult to format in Visual mode, or to change formatting, especially when pasting from a google doc or other application. It would be nice if you can swap to text (markdown) and edit it directly, or have the option to work in markdown instead of using the Visual editor without having to modify the default for everyone.
We do have an option under Account to disable live markdown rendering:
This is a setting that is at a user-level. We specifically created it for the times when markdown rendering is getting in way of writing sentences which contain markdown-like symbols.
We do not intend at the moment to have a plain text editor, but you can always use this setting, or simply export the page, edit in markdown on your favourite offline editor, and import it back.
Let me know if this helps.