2 feet, with the ball, in the endzone - whole possession. Since you can't fumble or advance a ball in the endzone - you don't need the "full" range of to the ground to be applicable here.If he doesn't make the whole catch then how can it be a touchdown?
You have to get clear possession first. We are talking about 7 points here. Not just some sideline.
The reason you would want this to be a rule in the field of play, again, is because not holding onto the ball through the catch would result in a massive amount of fumbles being induced. Since that can't be the case in the endzone, the "through" part of the catch doesn't need apply.
I mean - take the Chase factor away from this - and I still think that's the right rule to be in place here. There's no reason a WR with the ball, and 2 feet in the endzone shouldn't be a catch. It also removes the ambiguity of the call because we've seen catches made like this that have been upheld as TD's - how long does the WR have to hold onto the ball? Until he gets up? In the chase instance - how long does the defender get to rip a ball/hand away to cause an incompletion? So much is up for interpretation - in the endzone, that can be completely removed by simply stating that a receiver, with the ball, in bounds, in the endzone - has possession of the ball - is a TD.