I’d like actual examples instead of “I work faster”, something like “I can move straight to the middle of the file with 7mv” or “I can keep 4 different text snippets in memory and paste each with a number+pt, like 2pt”, things that you actually use somewhat frequently instead of what you can do, but probably only did once.
That’s just one thing the editing language does, though. There’s no single feature you can point to as the smoking gun; it’s all the small advantages added together that make vi worthwhile.