No, because then there will be people who will re-upload something that people have already made and sell it under a different name for full price, or take assets used by another modder and claim it as their own.
Which is the reason why paid mods died, and is the reason it needs to stay dead.
Ye-es, that's what I meant by "bodged" - if the mods were digitally signed by either the developers or the distributors, and only signed mods were allowed to be sold for actual cash, this would be a manageable issue.
It's not quite as pie-in-the-sky as you might think, Egosoft did something similar with X3: Terran Conflict back in 2008. A lot of the content for that was created in tandem with the X-Tended mod team. Members of that team were signed-on to Egosoft for the development of the game and their work was digitally signed by the devs (meaning you didn't need to enable "cheat mode" to run it).
Granted that was one, very closed and controlled environment, but it works as a technical proof of concept.
The new Unreal game will have a lot of community created content built in and signed by the devs as well.