I'm not entirely sure if I follow you. In the first play the receiver would be awarded the same forward progress even if he was going forward, caught the ball, was knocked off balance, extended the ball past the line to gain, had a non-foot/hand body part touch the ground and immediately lost the ball. The direction of the player is immaterial, what happens before he completes the catch is.
I don't have a big problem with the current interpretation. If the receiver is not going to the ground, secures the ball, has one foot down, and is then knocked off balance and loses the ball after touching the ground, it is a catch. If the balance is lost before the catch is completed, control must be maintained throughout the fall ("show me the ball").