I can only relate to my Rugby experience. Personally I was great a kicking the ball out of hand, I had a cannon on my leg and could find touch deep in the opposition territory from our 22 with ease. But in one game, our regular place kicker had some injury problem and they asked me to kick penalties and conversions. I literally missed every single time even lay ups, it got to the point where I was begging the coach to try anyone else but me. The last penalty we got in the game, which was in a good range for a shot at 3 points, I threw the tee away and just performed a drop goal, it was the first and only one I actually converted :)
I would imagine even with the lighter and smaller footballs, it's the same issue for a lot of these kickers/punters, that switching between the two techniques is far from straightforward.