Style management stands as a particular example. Now you must wade through dozens of unwanted canned styles to find the ones you've set up... if I remember correctly.
For the style mess and other UI regressions that I haven't taken the time to catalog, I switched to LibreOffice. Granted, I don't exchange Office documents with coworkers much. We use (also crappy) Confluence for most documentation; and if I just want to send a document to someone, I export to PDF.
I used to love Word. I used WordBasic to automate not only technical-documentation production, but also to parse and rewrite thousands of SQL routines on a DEC VAX system and save my company weeks of engineering time.
I hate Word now because Microsoft ruined its UI. Oh, and I detest the continual hounding to log into your "Microsoft account." Nobody wants your goddamned account, Microsoft. We all have PLENTY of accounts by now.