In my experience plugins and mods in general are better to be left at donation only for a start, if you see that the mod grows really big and e.g. you need more people to work on it and donations are not enough people usually handle that by releasing premium features with a small subscription fee on top of the free mod/plugin.
E.g. a plugin that requires a MySQL server connection or a website to display data which the creator would need to pay for is something someone could after a while if the plugin is successful and used by many ask for a small subscription to keep it going.
But other than that Bethesda tried it and hell broke loose, it was a PR nightmare for them and well honestly quite expected. That is why they changed it now to be free, they acknowledge that in their FAQ too:
Is Creation Club paid mods?
No. Mods will remain a free and open system where anyone can create and share what they’d like. Also, we won’t allow any existing mods to be retrofitted into Creation Club, it must all be original content. Most of the Creation Club content is created internally, some with external partners who have worked on our games, and some by external Creators. All the content is approved, curated, and taken through the full internal dev cycle; including localization, polishing, and testing. This also guarantees that all content works together. We’ve looked at many ways to do “paid mods”, and the problems outweigh the benefits. We’ve encountered many of those issues before. But, there’s a constant demand from our fans to add more official high quality content to our games, and while we are able to create a lot of it, we think many in our community have the talent to work directly with us and create some amazing new things.