This is a good thing. If this was ever allowed to happen, mods would go from the realm of player made modifications, to a realm of player made DLC. It would inevitably lead to an over-saturation of what is essentially DLC and lets face it is that's not what anyone wants. Modders have a right to be paid for their work, but modders already have other ways of getting paid and receiving donations for their work. If this ever happens it would usher in the coming of a new DLC dark age, where modders get miked like the downloadable content cows big corporations like Bethesda and Steam wish they could be.