But he was switched for another boss in the final version of that game.
Not so much switched as simple unable to be finished in the time frame.
Think of the Omega Pirate as going to be the pre-Kraid boss.
As for Ridley, well yeah, he has important story in association with Samus, Kraid has about as much as Crocomire or Draygon. --- "Nonsense, Bagan cannot be defeated". - Aliens: Super Godzilla Kool Frostbyte - XBL gamer tag.