To me it really isn't. :)
The DLC doesn't add features that appeal to me and I don't want to spend 12€ on DLC for a game I haven't played in years. :)

I asked the devs on discord and it is indeed a change in publishers that’s behind this. They will try to bring it back on Gog as soon as possible. See the attached pic.

I believe that's a game from the same publisher (Dear Villagers). Dead in Vinland has a different developer (Ishtar Games). Ishtar Games has a recently released game here - The Last Spell, I enjoy it immensely. In any case neither are leaving - just distribution rights going back to the devs and the game stuck in limbo until then.

Ah, nice that it will be back, I had it on my wishlist for ages, just waiting for a Complete version to show up. Maybe this time they'll release it like that.

Ah, so just bureaucracy. Thanks for asking.
(Of course, GOG could have provided those details...)

They might not want to tell us that. GOG knows some of us will buy games that are going to be removed.