Related to this I recall reading (somewhere) about going from a keypad back to a rotary dial and how infuriating it is even though there's only a tiny difference in speed.
We humans get used to the speed as little as it is and having to go back to the old way and it's only 1/2 or even 1/10 second slower drives us crazy.
The major difference is that with a keypad you can type at your own pace, while with a dial you have to 1) wait 2) a variable amount of time for the rotary to go back in initial position for each figure. Furthermore keypads allow "muscle memory". I'm not old enough to have used extensively rotary dials but I think it's very hard to form muscle memory with rotary dials. As an aside, I don't think the difference in speed the two is "tiny".
We humans get used to the speed as little as it is and having to go back to the old way and it's only 1/2 or even 1/10 second slower drives us crazy.