Life Cost 0 is the kind of skill that's either going to be broken or useless. There's no real middleground. Nobody's running the skill just so they can use that Autonomous Action Unit they topdecked at 200 LP. I don't see how nerfing the skill is a problem. It really only affects Stein and Destructotron, and cards like Cosmic Cyclone you're running in your Deck just to TRIGGER Life Cost 0.