It's described in the Keynote. This is the exact quote:
"For example, where you look is very personal. It can give away something about what you're thinking. In Apple Vision Pro, where you look stays private. Eye input is isolated to a separate background process, so apps and websites can't see where you are looking. Only when you tap your fingers do results get communicated, just like a mouse click or tap on other Apple devices."
I can't speak to whether extra controllers are a good idea for Apple. From the impressions I have watched and read from VR enthusiasts (e.g, Norm from Tested) they have very high praise for the input and UI. I agree with you, however. I don't think typical VR games will be big on this device