5 minutes with an existing eye tracker will show that this is completely infeasible. Your eyes move too much for it to work.

Perhaps you could use it to bring windows forward.

Because any time you're doing fine-grained work with your cursor, you're looking at it. I'm not talking about games.

I can see where you are coming from but it doesn't make too much sense to me. Why can't we have both.

it seemed pretty obvious we do have both. It showed a "magic trackpad" being used. Seems like it supports pointing devices normally.