Haptic feedback removes the most crippling weakness of the touchscreen, the inability to use it without looking.
I wouldn't go as far as to say that. But it does make interacting with a touch screen feel a lot more "physical".
That is, I expect the natural response to most of these feedbacks is to look at your watch. That not the case?
Not that they do it on the watch, but it could also have a ratcheting-type feel when you scroll to indicate a) that you're scrolling or b) how fast you're scrolling.
The Steam Controller actually used this to great effect.
That said, I don't drive much. At all. I do bike, so I have used the similar feature of the headphones I wear. Never wanted to try and use the phone.