Let's sum this up: to see what others have seen, and think what nobody has thought.

Okay, that's not my quote. But it encapsulates the idea.

You can be stuck in the weeds, and not have any perspective. That's pretty clearly a lack of vision.

But you can also be so high in the sky that you can't make out anything. Let's call that a lack of vision, too.

You can be standing on tracks and get hit by an oncoming train. "I didn't see that coming!" Also a lack of vision.

So what's that working out to? Being in a position to be aware of your surroundings, and being able to predict how they'll change for better or ill, perhaps?