defined ...
They have defined legal jump sticks, and as long as one uses a legal one, leave it alone ...
Besides, if you really locked someone up, like frozen against a ball, they would not be able to jump anyway. I understand both points of view, but I say leave it alone and allow legal jump sticks. You have to adjust your strategy within the rules and framework of the game.
30 years ago in Houston, I used to be able to get up on the table completely and get down on the cueball to make a shot, but I have to keep one leg on the floor now.
I must admit, though, that jump shots are harder for me to perform (5'7") than someone that is 6'2". Every sport has specialty equipment that makes playing the game easier.
I used to be a real good Ping Pong player and they were always coming out with special paddles for better english or better slamming.
Look at what the 3 point shot did for basketball. Sports evolve over time.
You have to adjust your strategy and play accordingly.