Well, say I want to go back a page, i move my mouse upto a button and click. If i want to go back 3 pages, I click thricely. (Yeah that's a word!) With mouse gestures you have to saw some kind of L shape. Which means you have to click, move your mouse one way, then the other and then let go. Presumably if you want to do that 3 times you have to repeat 3 times? Seems like much more work to me. Also having to draw a shape everytime you scroll down rather than just using a scroll wheel on a mouse.