If you also posted the mod for free, nobody would have a reason to pay for a re-posted paid mod. If you're both charging for it, then that goes into the realm of intellectual property. That's a change that could be painful in a world of previously free mods, but something not uncommon in other places.
It's an app store. The question comes down to: would you rather have an ecosystem of only free (or donation-driven) mods, or would you rather have some mods be paid mods? I really don't think the move to paid mods is as apocalyptic as reddit was making it out to be.
You’re assuming perfect information. Amazon sells plenty of ebooks you can get for free on another site.
Honestly, they could have pulled this off. If they made a new game with the option to sell mods and had some sort of review process doing due diligence that would have been something else. Or even some sort of auto check for conflicts. But, this seemed like a horrible money grab where they wanted to extract 75% of the income without doing anything.
It's an app store. The question comes down to: would you rather have an ecosystem of only free (or donation-driven) mods, or would you rather have some mods be paid mods? I really don't think the move to paid mods is as apocalyptic as reddit was making it out to be.