Because you're a good parent, you'll have taken every possible step to ensure that your baby stays pain-free as much as possible. You'll never have hurt them while touching them. Because of that, they're not really aware that hurting someone by way of touch is something that can really happen. That probably goes some way to explaining why young babies enjoy clawing at your face so much.
At first, it's adorable when they keep reaching up towards you; it's like they can't stand being away from you and they want to be closer. They grab your nose, or your lip, or poke your eyes. You swear that they're doing it on purpose, but you know they're really not. You know how the old saying goes, though - no pain, no gain! Whoever came up with that expression must have been talking about parenthood.