I think it can work but definitly not the skyrim way. If steam or developers want to keep a significant part of the money, they should have to do some work for it. The skyrim community is huge and there is an incredible amount of mods. Making it more organized would be a great idea. If those funds where used for proper maintanence, like (com)patches (maybe even integrating essental mods in to the main game), moderation or sorting out broken mods, it would be fair to charge for it.
Sure people could pirate mods but the same argument can be used for DLCs and what is the real difference between DLCs und Mods you have to pay for anyway? But I am not saying there should be no more free mods just that the modding communities have grown incredibly large. Compatibility and maintanance will only become a larger issue. So coordinating all this projects to work togeter becomes nessecary, but it might not be the kind of thing that people like to do for free because it is so much fun.