The argument against paid mods shouldn't be centered around price. The real issue I see is modding, especially with Skyrim, is a community activity. Many mods borrow from others or have dependencies on other mods. It's like open source coding--through borrowing and re-using existing work, the wheel doesn't need to be re-invented, and mod authors can focus on new features. This open atmosphere of sharing content and resources is what allows the creation of high volumes of high quality mods. Once you try to monetize that, re-using resources is no longer considered sharing, but stealing. And most major mods re-use resources to some extent. Gameplay mods probably use SKSE, SkyUI (MCM), FNIS, or some other framework. Some also borrow assets like item models. NPC mods generally borrow texture mods, hair mods, body mods, clothing mods, etc. The modding community for Skyrim is undoubtedly one of the most active modding communities out there, but it's also one of the most interconnected. The sheer volume of small mods is amazing, and that creates a giant pool of content to share and build off of. But attempting to monetize mods will destroy the inherent nature of sharing in the community, which is what makes Skyrim modding so successful.