Just further on the CNK/Garrick situation (normal posting not drunk gameday troll posting - sorry once again) - the reason the rule is like it is, and it makes sense, is because defenders need certainty on when they are allowed to make a tackle. Hence we have a very clear rule that when a player is receiving a kick on the full, you have to allow for the fact that he might jump.
In a situation with e.g. a bouncing ball off a charge down, the defender is entitled to think that the attacking player is going to behave "normally". The same goes for any normal hit up - if an attacking player leaps into the air before the defensive line, he would probably be penalised (there was a famous example a few years ago of Vunivalu doing this on a kick return). There are two reasons for this - the obvious one is that it's dangerous, but the second reason is that it's unfair play because it puts the defender out of play and gives the attacking player an unfair advantage.
With the CNK/Garrick example, CNK is sprinting to make a tackle and then Garrick jumps. If he isn't allowed to make a tackle at this point then CNK would've run past him with his momentum and Garrick gets an unfair advantage. The logical alternative would be that Garrick should be penalised.
As others have mentioned, imagine DWZ does one of his leaps for the corner and a defender hits him at the right angle so that he flips over and comes down on his head. I'd hate to see it happen but if the defender is just attempting a normal tackle then I think it would be ridiculous to penalise that. I am not criticising DWZ for leaping for the corner, but you have to acknowledge that he's the one putting himself in danger.