That costs money while getting somebody to do the job for you for free, is free.
Though now that I'm in a more lucid mindset, that logic, wanting CoC1 writers to do the heavy lifting, doesn't make sense.
... That was quite a tangent.
The summary of the above statements is this.
If you wanted to be a 3rd party writer, you'd write around tons of restrictions, have no control over things you write, have half of the roster be untouchable, have meta reasons blocking things you want to write (like B being barred from making a F/F pregnancy for Zo), and generally have to goose-step around every decision.
So where were those corruption writers supposed to come from and exactly what were they even going to be allowed to do?
Funny thing about that now that I've broken my one taboo. The person that wrote corrupt Amily, that content that people refer fondly back to, wasn't initally all that fond of writing it. Nobody knew this for months because it was done without complaint nor incident.
But that was back during a time when Fen was hungry.
Hunger led to all manners of things. Like adding things that people want purely for the love of being able to eat.
You know, now that I'm on that. TiTS just recently added a Slyvaren slave. While I'm not much of a fan of the setup and nature of the content (if the person doesn't come out the other side actually happy it happened, it's not for me), and it's clear from the comments that Fen isn't all on board on exactly happy how it went, even letting it in shows that Fen still has the grit to let people add stuff if they're willing enough to pay for it.
... Or desperate enough for content to put into the game.
Same result, really.
The addition to the summation of this string of consciousness is this. If they were able to fund these types of projects back when Fen was making a scant 1.5k a month, they could do so now making 29k (or is it 28k now? Irrelevant anyways)
Big Edit:
This is all in the hypothetical.
The statement "I don't want to do it" is really all that's necessary. They don't want to, it's their game, it won't happen. That's not a wrong stance to have.