Define backward.
To me, it is like the difference between a small text editor and a word processor. Using a text editor for certain things, instead of a full Word Processor isn't going backwards. It is just using the simplest tool that makes sense for an immediate need.
Same thing for "TidEdit". It is just about reaching for the simplest and quickest tool for an immediate need (just jot down a note) , yet having that WikiText available (and preview) for quick visual organization of that one note, however short/long, for later serious processing.
In a way, it boils down to that difference (in my mind, anyway) between note-taking and note-making.
I imagine TidEdit as something complimentary to TiddlyWiki, a really nice addition to a TiddlyWiki ecosystem of tools/components/workflow-enablers.
A simple HTML page with a text area on the left, preview pane on the right, and buttons for WikiText markup, and buttons for "new", "open", and "save", always working with TID files for each drag and drop into a TiddlyWiki.
Why would any "save" plugins be required? "Save" would be like "download", and open would be like "upload". Aren't those just basic javascript functions?
I suppose it isn't really about stripping down TiddlyWiki. It is about creating a single HTML file that provides something that is StackEdit-ish (no "notebook" and no multiple notes handling), with buttons that work like the tiddler edit buttons for WikiText formatting, and those "new" (clear text area and preview), "open" (pick a file and put the content of that file in the text area), "save" (i.e. just download a file that has the content from the textarea) buttons.