Jayemdae Tome saw some play in those days, so Greed was probably better than people gave it credit for in those days, but deck design was nowhere near the level its today
This means that a Karn deck doesn't need to concern itself with including many creatures to attack or block with, as it can be used to turn anything from an Unwinding Clock to a Darksteel Forge into an offensive or defensive body on the board
Goblins, primarily, will see a lot of use out of this, but so too will all manner of tokens decks
with combat tricks like Monstrous Rage constantly being advocated for the ban
Maximum Belt is an Ace Spec powerful tool card that gives the Pokmon it is attached to 50 bonus damage if they are attacking an ex Pokmon
It's not a terrible card, and what you may think is the worst part - the five life gain for an opponent can actually be useful as a political tool