There is one thing that i dislike in the idea of paid mods... the quality control and assurance. With the games producers you have some regulations that create a legal frame for the products and the business practice. With mods it would be a headache... if i will like some awesome mod like Long War or Third Age then i will donate, but forcing me to pay up front for something that is usually work in progress and in a lot of cases quality is not high up, is simply a bad idea. I wont mind seeing paid mods on steam once the mods are out of various beta stages and were approved as working as advertised by the game developer. Yes, game dev needs to get involved into the approval process if the mod is to make money to the creator AND game dev.

Exactly there have been cases with developers taking on modders (like with Project Zomboid) and actually taking them onboard as freelancers, paying them to develop their mod into the game itself. So do that, make especially good mods approved by the devs and become a sort of dlc, released by Bethsda, who pays the modder - while I would personally not endorse that by using it, it would be an official Bethesda product and the modder would get paid.. solves some of the most glaring issues.

Personally, I can't wait to start throwing fat wads of cash at Prosper.