Can you really explain why people would need those? Damn, it would be fine if they just removed the whole damn scrollbar. Who uses it anyways? Using gestures to scroll is way more intuitive and easier.
Yes. I use a mouse at a desk, and don't use a touchpad. The amount of "scroll" for each click the middle wheel scrolls is different depending on the scroll size - even in safari(!) - and having fine grained control was nice.