> I think that's already the case, isn't it?

afaik, only the stack height is regulated. Specific technologies like foam, carbon plates etc. are not.

> I don't understand why you would in the first place, what would be the reasoning here?

Personally I'd love to see more shoe development, but I image that if you feel that using supershoes during races is cheating, you'd feel the same about using them while training.