I really don't understand these cries about valve breaking the modding community. When I think of a modding community I think of Nexus, which is unaffected by all of this. Steam is a content delivery service and if they want to charge 75% profit for mod sales that's their decision to make. It's a fairly stupid decision but it's not like we're stuck without alternatives. All the best mods have always been on nexus either way.
I think the biggest issue is that people will make quick reskins of existing mods and sell them, causing a huge backlash from the original developers. Hopefully the reaction would be enough to reverse the decision if this hypothetical becomes reality. But either way as a consumer I don't really see how it makes a difference to me.
you're forgetting about the legal issues. for example, all the interdependencies between mods.
FNIS, SKSE, etc are required for a ton of mods, and these are just the most obvious examples. these are all under creative commons licenses. it's straight up illegal to profit from content that uses them without the explicit permission of the relevant developers.
the dev for SKSE has already said that he's staying out of it and letting people do what they want, but already one of the mods that was initially released as paid has been pulled down for DMCA infringement (some fishing mod that used FNIS, the author of which refused to participate in valve's bullshit).
are we going to be expected to pay for four other mods in order to get one working?
what about stolen mods being put on steam workshop? do you really think valve has their shit together well enough to process that kind of volume of copyright infringement complaints? their customer service is notoriously awful.
then there's the problem of the best mods on nexus being roped in to this, turning their backs on the people who helped them get this far and demanding money for a mod that has until now been free. Wet and Cold is an example of this that has already done exactly that.
all valve had to do was add a fucking tip jar
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i think my biggest issue with this is that it really looks like the beginning of much much worse. time has proven again and again that the slippery slope fallacy stops being a fallacy really quickly when money is involved. the obvious direction for this to head in is for game developers to only allow steamworks mods for the sake of profit. this wouldn't be a problem if valve didn't have such a monopoly on the PC gaming industry. mods are one of the main reasons PC is the best gaming platform, and this poses a serious threat to that.