I am now starting to wonder how much of it has to do with network access to Sharepoint and telemetry data that most likely didn't exist in the Office 97 dial-up era.
Features-wise - I doubt there is a single feature I use (deliberately) today in Excel or Word that wasn't available in Office 97.
I'd happily suffer Clippy over Co-Pilot.
It's an optional install. You can just click Custom, untick "Office Assistant" and other horrid bits of bloat like "Find Fast" and "Word Mail in Outlook" and get rid of that stuff.