They really glossed over the mouse issue. Without a pointer, using a mouse is worthless.

From a comment I made in another thread:

But for the mouse, the pointer (the little arrow, hand, cursor, etc. that indicates where your mouse is located onscreen) seems to be bound to only the VR controllers. When aiming a VR controller at the desktop, the pointer follows your laser thing. But if you try moving the mouse, it’s like the onscreen pointer is just invisible. It will activate the tooltips of page elements when you hover over them and stuff like that, and you can certainly click. But without actually seeing the pointer, a mouse is pretty useless. You can make the pointer appear by doing the “shake mouse to increase pointer size” gesture, but when you stop shaking, it disappears again.