Most modding communities see it as a creative hobby, something that they do for the love of the games and communities. Paid mods are generally not something they're very receptive to. These communities are mostly people who are into retro or indie games and reject modern gaming's various monetization methods.

There are exceptions of course.

A few things:

- Splitting your community is a concern. The classic example is multiplayer DLC: if not everyone can access it then it will risk low adoption.

- Presales and first week sales are hugely important to financing projects. Not many games achieve a long tail.

- Developers are expensive. Paying a team of artists and designers and programmers demands that they generate enough revenue to make it worthwhile.

AI opens this door because:

- Its capacity to be constrained fits neatly into mod frameworks.

- It's incredibly cheap to operate, compared to the human team.

- Users are comfortable with its SaaS model and so won't be deterred by a subscription model.

"and at no cost"

Leaked source code,flame wars, toxic fanbase making shitstorm why work with this modder but not that one, same idea as secret internal plans .. and unclear legal situation in general with hiring people om the other side of the world is what come to my mind why this is not happening more often. But it does happen sometimes, usually the modders get a individual offer from the company.