Modding has been one of the defining features of PC gaming for decades. The idea that you could modify the game you purchased - maybe add content, or restore features that were abandoned in development - has led to many games and genres coming into existence. Some of the most popular PC games today began as a mod; in fact, games that originate from mods now take up more than 11% of the share of the PC gaming community (in regards to playtime).
Needless to say, for many PC gamers, the topic of mod support is very close to home. Valve has supported the idea of modding in the past with the release of the Steam Workshop - the integrated mod installer for select Steam software - but for the most part, modding has existed as a microcosm, separated from any specific sales platform or limitations. Mods can be found on sites such as ModDB, Nexus Mods, or even a developer's (or development team's!) own website and, of course, for games that support it: the Steam Workshop.
Today, Valve has added a relatively simple feature to the Steam Workshop toolset that has elicited a very provocative response from many corners of the PC gaming community: the ability to make your published mods Paid Content.
On the surface, this addition seems like a no-brainer as modders should have the right to decide whether or not they want to receive some sort of financial reward for the work that they have done. It's the same logic used to defend YouTubers or streamers. Though - it might be important to note that many individuals are upset by this chain of events due to the inherent nature of modding scenes as a whole. Namely, the "modular" nature of it. Many mods for popular titles might take advantage of one another - in many cases, much like in other forms of software development, certain mods might depend on another mod's libraries. Another common trend is when some game's modding communities end up developing Mod Managers for specific titles - such is the case for Fallout 3/New Vegas, Sonic Generations, and many other games.
Valve's ruleset claims that any developer selling their mods through the Steam Workshop (in which only Skyrim is currently supported) will take only 25% of the profits, once their mod has breached a limit of $100 worth of sales. Additionally, any mod that you find trouble with can be returned and refunded within 24 hours, but that monetary amount will only be returned to your Steam wallet, as opposed to your real one. With regards to the issue of mods being placed on the workshop for sale by a party that had nothing to do with the development of said mod, Valve states that a DMCA Takedown Notice will be necessary instead of pre-vetting before an item is to go on sale. The same FAQ glosses over the issue of including other mods with yours, stating only that it will be possible for you to "allocate and approve portions of your item’s revenue with other collaborators or co-authors" and doesn't mention what should be done if one of the dependencies for your mod is from a developer that might not want to support portions of his mod being sold.
Already, members of the PC gaming community have created a petition to showcase their disapproval with the new system, but I don't think that the petition's author understands the biggest problem with this turn of events. The petition claims that mod development should be for the love of the game, and not for monetary gain, but it's important to note that the largest elephant in the room is the fact that this feature is flawed to begin with. If Valve can truly regulate the new workshop, then all the power to them and the developers that may want to get paid for their work - I just don't see it working when mod development has always been a collaborative art, and all it could really take to prevent a mod from being sold is one person on the chain of development that is opposed to it.
With that being said, I can't say I'm too enthused about the idea of paid mods in general - especially self-described Early Access mods. Additionally, I see potential issues with compatibility arising if paid mod developers have to end up straying their own path instead of developing with mod managers in mind (in an effort to prevent disputes, and to perhaps further separate their content). If anything else, the idea of pirating mods being a thing, to me, sounds incredibly silly.
UPDATE - It turns out that Valve had a set of Mods pre-approved, and there is in-fact a vetting period for any new mods going forward. As for the 25% of revenue that the developers take home - it seems that this amount will vary depending on the game, and will ultimately be up to the publishers discretion. Many of the same concerns still apply.