im going to do an awsner from a person that never played moded games;
For an amounts of games mods have been their saviours and for others are just for pure pleasure,
but mostly becuse there are not that much modded games exclusively for pc i tend to say that they should be free becuse its not fair for pc to pay for mods when you cant have them on playstation or xbox.
On the other hand there is the money gain that some of the modders deserve i think they should get payed, but 75% for steam that just dumb, steam makes so much money as they are now they could easily do a less paycut than that.
That is my opinion :P