Convert Word, RTF and HTML documents from Terminal — via SS64

The easy way

1. cd into the folder and run the command. It creates a new converted folder (and stops if one already exists) and writes a .txt file there for each .docx, so nothing next to your originals is touched.
2. Other formats: txt, html, rtf, rtfd, doc, docx, odt, webarchive.
3. Merge files into a new, unused file name: textutil -cat html -output combined-new.html ./*.rtf.

Command

Run in Terminal (Applications › Utilities).

mkdir converted && for f in ./*.docx; do textutil -convert txt "$f" -output "converted/$(basename "$f" .docx).txt"; done

Complex Word layouts (tables, images) won't survive conversion to plain text. Pick output names that don't already exist, because textutil replaces a file with the same name. To undo, delete only the files and folder the command created.