And what does "you can sure reduce it from what it is now" mean?
I'm going to try to give you some idea of how big a mess the catch rule is right now.
You currently have, in the rule book, at the same time, two different standards for determining completion of the catch process. One of them has been around for many years, and is popularly known as the football move. So that's what most of the current field officials have been using for most of their time in the league. In 2015, the football move was taken out of the rule book, and a new standard was instituted, stating that a player must "remain upright long enough" to become a runner. This resulted in so much confusion, that the commissioner appointed a "catch committee" to "streamline and improve" the catch rule. The catch committee decided that it had been a mistake to remove the football move, so in 2016, it was put back in, with specific examples.
But the 2015 standard was not removed.
So when Riveron said that James needed to maintain possession throughout the process of going to the ground, he was going by the 2015 standard of "upright long enough." The official who made the call on the field was probably using the standard of the football move (which has been around since 1942, with the exception of that one year). On the Dez play, there is no doubt that field judge Terry Brown was going by the football move, because that was the only standard at the time.
Which standard is better?
After a receiver has control of the ball and two feet down, there's a time requirement that must be met in order to avoid the scenario in which an immediate hit that knocked the ball loose resulted in a fumble. Both standards attempt to address this time requirement. The player had to maintain control of the ball
long enough to perform a football move. The football move is a clear, observable act that is either performed or not. The problem with 2015's "upright long enough" was that officials no longer had an observable act that they could look for in order to determine completion of the catch process. They had to use their own judgment in deciding on the point at which the player was no longer "upright, " and how long was long enough.
After the year without the football move, Goodell said, "We want to be able to understand better how we actually define how long they have to keep possession of the ball."
I'd say that was an understatement, and I'd venture to guess that at least some field officials simply continued to use the standard of the football move that year. In any case, the catch committee put the football move back in, specifying that "tucking the ball, turning upfield, or taking additional steps" were all things that established a player as a runner.
Take out "upright long enough" and it immediately reduces the amount of judgment that goes into these calls.