Yeah, it's got no grip and is shaped in a way that makes the bounce very difficult to predict. Besides, how often do you have to pick up a league or union ball at anywhere near full pace? If the ball is on the ground in league someone has either kicked it or there has been a knock on. It's hard to compare.
It's only got crazy flight if you can't kick it properly
Which brings me to another question of why more NRL players don't kick drop punts. I know Lockyer does (something I remember reading he learnt training with the Lions) and I've seen the Storm players do it (which makes sense). It would make 40/20s much, much easier.