That's a vary curious statement Mojo. What do you base that on? How can it be a non-issue if it's happened before and they've done nothing to strengthen the goalposts? Do you know something that we don't? Is so I'd like to hear it. Your assurances, based on what appears to be just a gut feeling, aren't very reassuring to me because my gut isn't saying anything except that it's lunchtime.
I'm hungry too dammit.
What i'm trying to say is that it's happened once right? Jimmy Graham incident. Caused a delay, player safety issue now along with excessive celebration rules blah blah etc...
NBA rims come down because 260 lb men dunk on them nightly, and every now and then they come down....naturally. Thats a part of the game.
NFL goalposts aren't going to start toppling(causing delays and injuries) just because a few players like to pretend to dunk over it on the occasional TD. Thats silly.
Its a matter of architectural structure and more importantly, wear and tear. This rule acts as though multiple players will be climbing on the goal posts after every third down conversion. <
I could see goalpost structural integrity being an issue at that point. 
I'm guessing here...i'd be willing to bet that any one single NFL goal post might get "dunked on" three or four times a season(less in Jacksonville

). The J.Graham incident was a fluke. Just don't hang on the goal post.
You see what i'm saying?