At the root of all this is the bottom and blatant fact that less people, in fact, way less people, will want to pay for a mod. Because of that, any revenue and popularity that comes out of this will be small for mod authors - especially if they have free versions of their mods out there (or if most people already have their mods). Add to that the disproportionate percentage they get. I support a mod author's decision to make mods free or paid, but I'm saying that it logically makes sense that a large number of people won't pay for modded content. However, I can't imagine why Valve or Bethesda would want to do this in the first place - the modding capability of Skyrim is among the biggest factor for people who continually play it to do so. Why they would hinder that, I don't understand. If it ain't broke, don't fix it.