So, does anybody know why there's no Deluxe Edition on GOG or any extras at all???

Kind of weird if you ask me...

...You mean the Director's Cut? GOG sells that already, if that's what you mean.

No, I meant the Deluxe Edition of Shadowrun that comes with soundtrack, some short stories and an art book(you can check it on Steam).

The one you are talking about goes for Dragonfall...

That's news to me, didn't even realize such a thing existed.

They had quite a lot of problems with the license:

What's the Deal with DRM-free and Other Questions

While they did manage to negotiate for DRM-free editions to be sold on stores like GOG, unfortunately I don't think they were allowed to sell the Deluxe Edition extras DRM-free.

It might be a good idea to bring it up on the official forums and ask if they can look into it again.

On the last Steam sales, I bought the Deluxe game (less than 8$ if I remember correctly, but that's been months agos). Worth the price, even if that meant that I was also paying for a game that I already have (but I am a fan of the universe, so I do not care). Hopefully, the same (or even better) special will be there in the next sales.

That being said, the Soundtrack is now included with Dragonfall : Director's Cut. The short stories/arts are still missing though.