That glitch saves time on the final screen by allowing you to jump into the green light without having to slow down to land on the pillars. The top runs by me, Thee_Deadguy, and CrabbyCrab101 all use this strat to save time there if you want to see it performed.

Otherwise, so far as I can tell, it isn't useful because going down there will make it more difficult to kill enemies which will cause the game to lag. A significant portion of speedrunning this game is lag reduction which is predominately done by killing enemies.

We have that in Super Dodge Ball and I really love it so I'm down for this.