The issue the NFL had was they went away from the intent of the rule and then micro-managed it with replay.
The intent was not to have going to the ground trump the catch process, it was there for giving a requirement for when the catch process was not completed so officials could judge a catch. The rule was officiated and written that way until the Dez overturn. They then tried to adjust the rule to make the bad call in GB the correct call and it went down hill from there. That is what is making it difficult to write the rule now, they are trying to fix what got broken by misapplying the rule and then changing the rule to cover it, without coming right out and admitting they got the Dez play wrong.
There is nothing wrong about going to the ground being a rule when it is applied correctly as an additional requirement when control, 2 feet, and a football move did not happen. But thanks to Blandino it gained power that was never intended because he applied it as being the only requirement incorrectly in GB and then made the rule fit the mistake.