All mainline Yakuza games appear to be on GOG up to Yakuza 7. But several of the spinoffs have yet to appear, and 8 has been out for over a year with no GOG announcement.

How did the Yakuza games arrive on GOG originally? Spread over a period of months/years? All released simultaneously and then nothing more?

Pirate Yakuza is out today and I'd really love to play it, but Sega doesn't seem to be giving us love lately. What are people's thoughts on the likelihood of Pirate Yakuza and 8 arriving here eventually?

Yakuza 0 to 6 were released together and Like a Dragon some time later.

They're simply still selling well enough on the other platforms for SEGA to even consider bringing them to GOG.
Once that's no longer the case and the sales elsewhere are slowly drying up they're going to list them here eventually.

I wonder if studios have anything to actually justify why they don't release DRM-free copies as standard. It's kind of a joke that GOG would have to beg for games, even when a lot of them are already cracked anyways.

Well DRM is the world wide norm, and GOG is like a small light in that darkness.
DRM was around long before GOG popped up, and is based on fear.

Out of those who do provide a DRM-Free version to GOG, they only do so in many (maybe most) cases, because they feel their game has kind of reached end-of-life sales wise, so they opt to obtain some more sales via GOG. In other words, they feel their game has become almost worthless, but they can get a little more profit by making it DRM-Free.

Sounds about right.

Speaking from firsthand experience, Sega is insanely slow to move on supporting new platforms, so I can’t say I’m terribly surprised. That said, I would’ve hoped to see the Judgment games here by now, at least. Obviously, there’s a pretty massive Sega catalog beyond the Yakuza franchise that it’d be good to see more of, too.

Sega Europe operates pretty independently, so I’m hoping they finally give us Company of Heroes at some point. 2006 seems plenty old enough at this point.

I don't expect the Judgment series to be released here. It appears that there was a dispute between Sega and the talent agency that controls the image of Takuya Kimura, who lends his image to the series' main character. The agency didn't want a PC port of the game, likely because modders could alter the use of its star image. I guess, just a speculation, of course, only a DRM-controlled version was allowed so that the publisher could guarantee that its users would not affect the integrity of the files.

Either Sega is waiting a bit more to release another batch of games (to get more sales from other stores first), or the series simply underperformed on GOG and there are no plans to release the newer entries

Let's hope is the first case!

The justification is, that we (= the consumers) are not trustworthy.
And we prove that...time and time again.

Latest response to that (deserved) lack of trust:
come next Wednesday, Amazon will no longer allow customers to download their purchased ebooks to their PCs.

I guess, that decision has (at least in parts) something to do with tons and tons of "how-to-remove-DRM-from-your-kindle-books" - videos on YT.

See: it sure is nice, being able, to remove the DRM from your kindle ebooks, to then be able to load them on other e-readers, tablets, etc.
But - as a side effect, that also enables you to share your kindle books with others, who didn't pay for them.

Now, I know, what you're about to reply: "I'd never do that!"
Hey - me neither!

But tens of housands, if not hundreds of thousands or even millions worldwide, don't share our code of honor.

So, often enough, what appears to be (unprovoked) actions of companies, are in reality REactions...to things we (= the customers) do.

Well, what I mean really is can it be shown in numbers that DRM-free harms sales in an impactful way.

For example, KCD2 has no DRM and was already available on the high seas by release. In spite of that, it instantly profited in 24h and sold far more than what it cost to create it. In this case, we can see that KCD2 being DRM-free didn't harm the game sales, like at all. Or, I would have to believe that adding piracy protection would have improved sales by the 1000s, 10,000s, 100,000s, 1,000,000s?

Question: how many additional copies of KCD2 were shipped over "the high seas"?
That's (theoretical) revenue lost.
Now: would ALL pirates buy the games they pirate, if there was a DRM around, which would keep them from pirating?
No.
But a decent number would.