And I would argue that paid mods make the developers more productive, since they are competing with modders. Why should I buy broken DLC if a modder can do it better?
I know this comment is somewhat old but I need to reply for this.
Actual modern economic research strongly suggest otherwise due several things.
At it is the mod community is a voluntarily, community driven project to enhance the games we love.
Now the system gets turned into a capitalist setting, where everyone is competing against each other instead of working together.
By the pure basics of economic theory, the prisoners dilemma prevents a new Nash-Equilibrium (wich existed in the volutary community by the way)
which is the goal of all economic activity more or less. The best possible outcome for the society. This happens due a lack of trust, as nobody wants to get shafted over and will
always choose an action that surely benefits yourself...resulting in a net loss of productivity.
Also a community driven activity thats free, is driven by intrinsic motivation (means doing things for your own pleasure, self-fullfillment or at least non materialistic gains),
but when modders are getting paid they loose this factor as they will now feel like an employee who "has" to deliver. Intrinsic motivation is traded with extrinsic one, here money.
Research proves that extrinsic motivation is far less effective than intrinsic one and needs huge amounts of it to even reach the level of intrinsic motivation.
This surely goes solely for work that was previously unpaid, as there was a totally different connection to your work. This also goes for the "customers", while a lot of people understood issues with compability or bugs, when they were free mods, they wont be as understanding once they get charged. People will develop the attitude, if they pay, they derserve, something a small modder wont be able to keep up. This is also scientifcly researched.
Here are my sources(among others) so you can see i don´t lie:
Successful Management by Motivation: Balancing Intrinsic and Extrinsic Incentives
by Frey and Osterloh
http://www.openlogic.com/resources/...o-external-rewards-kill-intrinsic-motivations
https://rkportfolio.wikispaces.com/file/view/Butler 1988.pdf
http://pages.uoregon.edu/harbaugh/Readings/Misc experimental/gneezy 2000 QJE pay enough.pdf
So the general assumption that by start to pay modder their work will increase is wrong. I might add that this assumption is actually so entrenched into Neoliberal minds, that they cant get away from it. This especially true in US/UK Universities and teachings since von Hayek´s rampage under Reagan/Thatcherism.
Sorry if I made mistakes in my spelling, im no native and my keyboard is not my friend, even in my mother language.
Edit: For the main topic: the only way I can see this happen if Paradox will curate the mods (only let big, non-copyright violating total overhaul mods being monetized with proven support) and sets up a set of rules regarding usage of assets like a fair use clause for free mods. Also Paradox would have to create a rule set for the split of royalties. THEN I could see it someway working....the wild west approach of steam will hurt modding more than they think....regardless what free market radicals say...markets do need juristical security! And even then mods like AGOT are at risk of being shot down!
Edit2: Ok just saw i misread the post i was quoting, he was actually speaking about paradox himself...so just see my answer as an argument aginst the common argument that"paid mods will increase quality"