Probably because that section failed, sadly.
You need classics first, indies later.
But the movie industry loves DRM and streaming.

I'm so down for some Vincent Price flicks in 4k on gog, even better get the silent horror films like Caligari and Golem

Not entirely true.

A well-targeted special interest niche selection can work perfectly.
The problem is that GOG first announced that they are opening a movie section, and when that didn't go anywhere they renamed it "movies for gamers" and then forgot the whole thing.

But there are a good number of game-related indie movies that are not on GOG, and I would guess that GOG hasn't even made any effort to get them.

There are also other ways to expand TV/movie section than Western mainstream.

I follow some Asian TV shows, but because I can't get them anywhere legally, I must use torrents or whatever to get them.
So having a different kind of niche like that, which isn't indie, but for a selected audience, could work as well.

But if the entire section is just abandoned, and they don't even have those movies discounted ever, then it's really going to fail for sure.
You would at least expect to see Cyberpunk: Edgerunners here sooner or later, right?

I expressed the same wish, but other people said that it could be tied to Netflix -_-

You mean "Motivational growth"?
It's still in my library. But it's gone from the store, don't know why.

The whole project failing is no reason to stop selling what's already on the servers.
More likely is that the makers didn't want it to be on GOG anymore or have some legal issues.

Contracts expire, and GOG clearly decided years ago to stop pursuing films or promoting most of those they still have. It shouldn't be surprising that they're not bothering to renew expiring contracts for films already here.

I'm not so sad that this venture failed, given how hilariously wrong it went.

But given as others said above, the industry is trapped and fraught with temporary licences, expiration dates, contractual jargon, and "you didn't renew this royalty cheque for the appearance of a Ford."

No really, vehicle licensing is a bitch.

Given the fine selection of er, "films" that GOG chose, I'm surprised some of them haven't been pulled down for becoming an embarrassment in retrospect.
Specially' Indie Game: The Movie. It'd be easier to name who appeared in that who hasn't come out with dung on their hands.