I used to buy into the notion that if you pay attention you won't get hurt. But I've had a couple of hard hit line drives come my way down the 3B line this season that would have been almost impossible to avoid if they were right at me. And I'm fairly mobile and I know how hard hit baseballs behave.
I'm all for the nets now. The ones they have at MLB stadiums are very easy to see through so I don't see the harm in having them.