Short version: The switched printers between the time they got the quote and the time they fulfilled, and they inadvertantly forgot to invite the linen finish as a request of the new printer. As a make-up, they included two additional cards.
Text from the KS Update:
While we're very pleased that Quests of Valeria is fulfilling on schedule, it was not a total success in one regard – the game cards do not have the linen finish that was unlocked during the campaign. There's no one to blame for this but ourselves. The quote with our original manufacturer included linen finish, but when we shifted to a different manufacturer, the linen finish was simply forgotten on our RFQ. Through the proofing process we failed to notice the omission until too late.
Since the linen finish was cosmetic and had no effect on game play, we decided (stupidly, in hindsight) to not post an update about it, but we did decide to include two additional promo cards in the game (Grendyl the Half-Fae and Ash the Chief Justice) as an apology. With that decided we promptly forgot all about it until a few EU backers commented on the smooth cards. What's even stranger was that we even forgot that we'd included the extra cards as an apology. It wasn't until we looked back through some of our old production notes that it all came back to us.
What did we learn? Double check our RFQs, extend our transparency to cosmetic as well as functional issues, and keep a tickler-file to remind us of what we've decided (and why) when issues arise.
So, I made this offer in the comments page, but I'll make it here again so everyone can see it. If smooth cards is a "deal breaker" for you, just let me know in an email to firstname.lastname@example.org. I'll refund your pledge and ask you to donate your copies of QOV to a school or library that may be able to make use of it.
I doubt that the "deal breaker" offer is available to retail buyers since I don't think linen finish is a promise on the box, but I included it as a reference for posterity.