This is a suitable workaround for this problem & the "Create Table of Contents Note" feature makes this much easier.
As stated in the original post, an example of the workflow that drives this need is having an "Inbox" notebook where all new notes are compiled which need to be processed on a regular basis. This processing includes:
Cutting and pasting new note content into an existing note to add to a ToDo list (or any other type of note)
Adding / Creating / Modifying tags as needed
Creating new notebooks, and/or reorganizing notebooks
Since processing the new notes requires a heavy use of the main Evernote Client window for search, and modification, it is a pain in the butt to have to navigate back to the Inbox after each item is processed. This is why having 2 main Evernote Client windows open at the same time would be helpful
The Table of Contents Note is workable, but I still +1 the originally requested feature