Well, first off, you still have to set up grinders, they can't be placed there for free. Secondly, the hitbox on j.D is not as good as the forcebreak. No where near it actually I think.
Also, btw ICPM is a finicky way to try and get knockdown, only comboing from j.H if 1. The spacing is correct and 2. There isn't too much hitstun decay. Fb buster brought potemkin not only a great damage tool, but you where also setup for optimal okizeme setups. And Pot had swag air-combos too. Ever see the AC FAB air combo? Shit was sick.
And people didn't burn meter on fb simply because they were there, but because that and FRCs where the most reliable and useful ways to use tension.
It wasn't super useful if you used a character that didn't have really important fb like sol, but even then you didn't use tension much unless you wanted to frc gunflame or do wierd shit.
And then you have Slayer. And Big Bang Upper combos.