Missing an extra point used to be something that just never happened in the NFL. If it did happen, the kicker that missed it or the holder that caused the miss were ridiculed. Missing a 20-yard field goal essentially never happens in the NFL, and in the final year of the extra point coming from just 20 yards out, only eight extra points were missed in 1,230 attempts (0.65% of all attempts).
Wanting to increase the difficulty in basically a given scenario, and to also increase the number of two point conversion attempts, the NFL competition committee approved a change to the rulebook for 2015 that instead of the ball being placed at the two yard line, it would be moved back to the 15-yard line, which is a 33-yard attempt.