As long as I can upgrade the base version at any time, I don't really care. But it gets annoying when the only option to get the extra stuff is to buy the deluxe version. I got Divinity: Original Sin from their latest Kickstarter campaign and if I want the soundtrack the design documents and the artbook, I'm supposed to pay $78 again. That's ridiculous.

I think the problem is more a labeling issue than anything else.

There needs to be a distinction between a "Deluxe" edition and "Collector's" edition of a game when it comes to game labeling.

The things you mentioned OP: Art Books, Soundtracks, Makings Of and Storyboards, should all be part of a Collector's Edition of a game, since they contain things only COLLECTORS would really be interested in.

While a "Deluxe" Edition of a game should naturally contain extra game content for the game, since it indicates this purchase is about the deluxe experience of the game itself.

And maybe a "Complete" Edition that contains both the collectors materials and the extra content.

But whatever the labeling, I feel there needs to be some kind of consistency to avoid confusion

I saved a couple of boxes which I did feel had some artistic value, like the Fable (1996) box which looks like a book, or Falcon 3.0 because it had such a thick manual etc. that getting rid of the box wouldn't have saved much of room.

Two biggest wrongdoers in my whole PC collection were The Journeyman Project Trilogy which had a gigantic box which could hold an infant, but had nothing else inside except the game CDs in cheap cardboard sleeves (not even plastic CD jewel cases!) and no real manual IIRC, and Leisure Suit Larry 5 which also had bigger-than-the-norm cardboard box with almost nothing else but the diskettes and some leaflet manual inside, I think.

I've never paid so much for mere air!

I don't mind deluxe editions as long as the normal edition contains everything that is supposed to be in the game. I consider extras as fluff. Nice to have but wouldn't necessarily pay extra for them.

GOG made it a standard to include bonus content for free and they continue to do so when possible. It's quite obvious that the developers/publishers aren't willing to provide the content for free and GOG end up in a position where they can only provide it as a paid extra or not at all.

Correct,it's been going on for years.They release a game then upgrade it and call it a fancy name and keep re-releaseing the games as (whatever) with tiny little extras added.

More goodies.

There's a lot of that, but it also has to do with GOG being willing to release games without any goodies. Back in times of yore, having goodies was one of their selling points.
Between releasing new games and releasing old games without it, they've given up all their leverage on the issue.

Now, whether or not they could have continued without either is an exercise I leave up to your imagination. I get the sense that it was inevitable one way or another.

There's true to that. Pillars of Eternity was definitely overdoing it with three different, obscurely named, editions (hero/champion/royal).

I kinda dislike that they call these extras upgrades as "DLC", because I've normally considered those to include some extra gaming content, even if it is merely cosmetic. A bit like if some old PC retail game would have received an "expansion pack", which included nothing more than making-of videos on a DVD, the soundtrack and an extra cartoon. I think people expected expansion packs to include extra gaming content, not just fluff.

Anyway, as long as GOG makes it as clear as possible, what are the differences between the different editions and what different DLCs contain so that I know easily which set has all the gaming content, and nothing more.

As a specific scenario, generous backers of a kickstarted game might feel betrayed if all the higher tier rewards got included for free with the game for everyone. Simultaneously it's nice that they're still available at all.

They should at least collate the different editions of one game onto one store page. It's annoying when there are multiple versions of the same game in the catalogue. Pillars of Eternity is a good example of this. I wonder how many people accidentally bought a more expensive version or the same game twice of because of this.

:'(