The "reason" (lie) for doing this was because some exotics don't have catalysts, Bungle is to lazy or inept to come up with Catalysts for them so they need to wreck everything else to add this in. Of course the obvious thing to do is make orb Generation an intrinsic ability for all Exotic Weapons - regardless if they have or don't have a Catalyst, but this is Bungle we are talking about, whose can't make a simple change without involving major changes to the games. The real reason Bungle is doing this is to make us weaker and slow our progress in the game. By removing orb generation for all our masterworked weapons (sunsetting them), they slow our already nerfed Super regeneration rate even lower, make our "Charged with Light Mods" useless, force us to choose either Orbs or Ammo Finder mods for our helmet and make us less powerful. It's basically Destiny 2 Y1 "Go Slow" all over again with a dose of Weapon Vaulting on the side..