There's nothing fundamentally wrong with the concept of modders wanting to get paid for their hard work. The system as implemented on Steam workshop is goddamn awful though, and the cut that Valve is taking out of every sale is nothing short of absurd for a game that they didn't even ****ing make. I'd feel better if there was full disclosure on how much of that 75% actually goes to Bethesda.
As is, I'd rather modders set up individual Paypal donation links or a Patreon so I'm at least somewhat confident that the modders themselves are getting their fair share. I can't willingly spend money for anything offered over Steam workshop knowing how much of a pseudo-monopoly it is over digital distribution on the PC platform already, because that's just going to give them free reign to **** everybody over even more in the end.
The only reason mods were free previously is because there was never any good way for modders to reliably get paid, but with stuff like Patreon around, that's becoming less of an issue, and they can get their fair dues without putting even more power into the hands of Valve.
Right now, it's pretty much horse armor territory as far as I'm concerned. Just get your mods from Nexus and donate to mod authors wherever possible through external means.