Why can’t NFL players hold on to the ball before they score touchdowns?

A rash of embarrassing incidents at the goalline threatened to cost teams dear on Sunday as players failed to master the basics of the game

With 3:16 left in the third quarter of the Bengals' 37-27 win over the Titans, Tennessee running back Tony Pollard fumbled, and the ball was recovered by Cincinnati safety Jordan Battle. Battle had a clear lane to the end zone and a 61-yard touchdown, but he instead decided to celebrate his touchdown before it happened, dropping the ball before he crossed the goalline. The ball went out of the end zone, which meant that the touchdown was instead a touchback, and the Titans got the ball back at their own 20-yard line.

Not that the Titans were able to do anything with that additional opportunity, given their putrid passing game, but why do so many players - some of the best athletes on the planet - forget how to hold on to a ball when near the goalline?