Comment 7 for bug 1080283

Well, how it's currently done on the primary screen is definitely not how you would want it. It's very user unfriendly, because it's hard to hit the corners in the middle, while you can also easily hit it by accident when you are going from one screen to the other with the mouse. I think it's fairly logical to put the hotcorners on both outer sides of your total screen, as multiple monitors are meant to extend the total screen real estate you have.

The fact that the dock and panel do this is because that is the most user-friendly. Hotcorners are a very different kind of control system, they actually are less user friendly like that. You can't really compare those two as they serve a pretty different purpose and act in pretty different ways.