The problem is that it's a kamikaze button. You're flatly more vulnerable in Splashdown than you are normally, and its AoE is ginormous. It's easier to splat the special user than escape the blast radius in most scenarios. It will only not be flawed in my eyes if it becomes the other way around. It'd be nice if Triple Splashdown (and Ultra Stamp, for that matter) gave the user armor when activated.
I respectfully disagree I think specials that put you in a vulnerable spot can be a really good thing for design
Now you can take it to the extreme like with reefslider and og splashdown but think of all of the best designed specials they all have some amount of Splat-the-user counter play
The rider is exposed on Crab tank
Inkvac can be damaged from behind and by melee weapons (this still needs buffs)
Inkjet increases your hitbox size
Zipcasters zip armor is only when you are zipping and is very weak
Ultra stamp can be shot from behind and from the sides (and from infront which should be fixed)
And triple splashdown can be shot out of the sky
This allows interesting counterplay and the feeling of a fair special if balanced properly on both ends
Triple splashdown also has a decent bit of skill expression for the user AND the fighter
You can aim the fists
You can use terrain elevation changes to place the fists above you or below you
You can splashdown super jump (don't do this)
You can splashdown over splashwalls and brella shields (sorry fellow brella players)
And for the fighter you can
Shoot the fists close to you
You can kill the user (which is a trade off because you might die to the fists)
You can run away
You can punish the landing
I love this specials design and I really hope it comes back in Splatoon 4
instead of stingray or some other trash special in terms of design