Re: Wrong question
If you feel the need to watch your speedo constantly to know what speed you're doing, you shouldn't be driving a car. Similarly the person who needs a constant reminder of the speed limit.
If you run a small engined car or an eco vehicle, fine, that won't vary much in speed even if you accidentally put your foot down. If you have the kind of car which goes from 0 to "what seems to be the problem, officer" in 7 seconds you have to pay a little bit more attention - hence the use of cruise control.
Personally, I feel a lot safer with some power under the hood as it gives you more options to avoid idiots (this is assuming you don't abuse that power, I have seen that happen too, usually followed by an abrupt attitude adjustment courtesy of a tree).
Biting the hand that feeds IT
