Concatenating files feature (quickly and easily joining files)
Many years ago I used Wordperfect and it had a great file concatenation feature and I'm surprised Word has never developed one. This procedure is specifically for people who write documents in parts, eg, a book with a different file for each chapter. As I remember in Wordperfect you just typed something like Book=Chap1+Chap2+Chap3... This produced a file of the entire book.
There are a LOT of people writing books these days: fiction, memoirs, etc. Many use Word. My books usually run to more than 40 chapters. If I want to send a draft to someone I hate having to spend a great deal of time and effort to copy 44 chapters into the end of chapter one (and sometimes making a mistake in the process!) before sending off the book draft. A file concatenation feature would be useful for writers of many types of documents.