There is nothing there that labels them as an bonus that will only ever be available to Kickstarter backers. Only that it is being given to Kickstarter backers as a reward. It could be given as a reward for other things as well (promotional, pre-order bonus, CE item, etc).
And, by the way, I've had more than enough "exclusive" pre-order and CE bonuses eventually become available to everyone to know that the term "exclusive" usually only applies to that moment. i.e. "this item is currently exclusive to this group at this particular time, but will be available to everyone at a later point.". Developers rarely hold to the exclusive promise the way people expect (not that it matters here, as the term exclusive was never even used).
They could but I doubt it for the simple reason this is a more touchy situation than usual....we're talking about backers who pledged on faith. Without them Original Sin would be a much lesser game. I'm not overly concerned about this myself but I can see how some people would be upset. And this isn't a publisher looking to nickel and dime every bit of DLC imaginable like all the preorder bonuses that later went on sale. But I'm sure modders will make them more widely available so I don't really get the concern here.
I honestly don't see anything touchy about the situation at all, because at no point were these particular digital items even described as being exclusive to kickstarter backers, only that they would be provided to backers as a thank you for their support.
That's like me buying a pizza as a "thank you" for friends who help with a move - it doesn't mean I don't ever plan on using pizza as a reward again.
There was no promises attached to these items, except to deliver them and create a better game. So, I don't know why anyone's faith would be at risk as neither promise is being broken.
As Larian is already saying they've gone over-budget, it's obvious they relied on both Kickstarter funding and Steam Early Access sales to continue enhancing Divinity : OS.
*Both* groups contributed towards the development of the game (in fact, it'd be interesting to hear exactly how much money was raised through Steam Early Access versus Kickstarter, as we know how much was raised through the latter). Now, Divinity : OS on Steam costs $40, which on Kickstarter would have gotten someone:
2 digital copies of the game
1 digital soundtrack
2 Kickstarter potions
Zandalor's Trunks of Epic Intelligence
A listing as a backer in the credits
A Kickstarter forum badge
..but instead they (Steam backers) only receive a digital copy of the game. If anyone should be feeling a little upset, it's them. Usually games available through Steam Early Access are bundled with early back rewards as an incentive to buy in early, but for some strange reason Larian Studios decided not to do that despite offering these rewards through Kickstarter (which not everyone pays attention to).
