So I've read into this, and I think I can flesh out my opinion a little more.
I don't know if anybody's going to read this, or care, since the thread is moving at 20 posts a minute; but as a modder, this is why I think that though this seems anti-consumerist right away (it is), in the long term I feel like, if this catches, it'll set a horrible precedent for the modding community from now on.
For why you should or shouldn't listen to me: I'm not very popular on Workshop. I only have about 20k current subscribers, and I've only published what I feel would be better in the community's hands than in mine. I'd say 99% of my 5 years of effort and dedication are hidden somewhere on my harddrive, and will be for a long time. I'll admit I'm given a paid commission every once in a while, but only once, ever, have I had a guaranteed audience and significant payment.
But I do have one thing in common with them - I know what unrewarded hard work feels like. I've gone months upon months on end, many different times, working on something purely out of passion and hype for the community; though I've only released what I've been obligated to and what I believe holds up to my standard of quality, which is that it brings something new and desired to the table (that would be 3 things total in the last 2 years, for a grand total of roughly 450$ from commissions that didn't scam me).
But if I could upload whatever I felt like, all of the rehashes and unfinished piles of

, if people
had to reward me for all of my work - frankly, I'd love it. Getting paid to do what I love is the dream I strive for, and the same is most likely true for them. Ignoring the 25% cut, it sounds like a really good idea for me as an individual, in that moment.
But, here's the part you care about - I've seen this happen at least twice before.
This was back in 2010 so I'm probably missing a lot, and somebody else already made this point, but I'm gonna talk about Minecraft. At first, something so modular and easy to access with infinite potential and a huge audience was almost unheard of. For people who only saw it now, it's hard to imagine the vibe was once casual. From what I remember, it felt like LEGO fans and DND nerds got together just to swap ideas and share code. But after a while, more ambitious mods kept coming out. The attitude slowly shifted to 'I'll make this because it's cool, if people want to support my effort that's nice' into 'for X amount of effort I require to be compensated Y$' - until somebody found ad-fly, and it spread like wildfire. It didn't happen right away, but things changed. If a download broke and somebody tried to mirror, the creator would be rabid on their ass. If you shared an idea, somebody would passive-aggressively tell you off. If you asked for help, people would treat you like you were trying to steal their 'X effort' so you could collect the 'Y$ compensation'. It was all super-serious numbers; greedy people with low talent saw the cash train and tried to jump on, and started throwing people out once it hit capacity. The 'X effort' bar got lower and lower until everyone else became an enemy. If you talked to another modder, they were just someone trying to steal your ad-fly pennies/OC donut steel concepts/'fanbase'.
A similar thing happened again with the GTA modding community, on a much smaller scale but far more competitive. What was once passion fueled by donation, transformed overnight into a sense of entitlement once free money became involved via ad-fly. A pretty significant amount of people saw it as a cheap 'opportunity', so about every 3rd new mod released on a given site was created solely to cash out by a few different means (either filling a gap or adding your OC donut steel to an existing one). Through lack of an audience, these cash-4-mods could only sustain themselves by trying to maximize your audience, which meant to them eliminating competiton. New talent was IMO almost seen as a threat, so were shunned and insulted out of forums (me included!) for asking for help. Very little documentation was published, partly because of this incentive to keep people out. Creators did whatever they could to eliminate 'competitors', mostly by publishing hitpieces and badmouthing other modders, though IIRC a few doxxes and DMCAs were attempted.
This is really speculatory, but I see the same thing happening very easily with Workshop if the paywall spreads anywhere else. Once a significant amount of mods are set at arbitrary prices, existing modders neutral on the issue think 'Hey, mods similar to mine are priced at $5. If I price my mod at $5, that's guaranteed money for me, since everybody else is successful with theirs'. More and more will probably begin to change their tags to accommodate an imaginary economy, that X effort deserves Y payment, until the line of thinking slowly mutates: 'If I eliminate one free Y mod (my own), that's a little bit more potential profit in the Y market that could go to me. If I find a way to eliminate my competitor's rival Y mod, that's one more. If I could stop people from learning how to Y mod and X mod, my potential cashflow would have x3 the opportunities to get an audience.' It slowly turns modders against eachother, at the cost of everyone involved.
And even if introducing this payment doesn't make existing modders change their mentality due to friendships and communities, you can bet your ass that the low-talent, highly-competitive 'capitalists' that saw an opportunity in Minecraft/GTA/pretty much every other game with modding potential would descend like locusts. This time, it wouldn't be for pennies, but $10, $20, $30. That's x100 the cash that ad-fly caused so many communities to turn against eachother, stagnate new talent, or sometimes destroy communities. They would take over and flood a given market to try and maximize cashflow - bonus points if they start fights with other modders/eachother, alienate new talent and stagnate the market.
It's happened before - people will always abuse cash systems like this. I can't stand in favor of this happening to the communities I love.