gooberking: Until people start handing out their unused steam keys, or swapping them for extra items.
Honestly Steam keys are easy to acquire through every other vendor. There isn't any great reason for GOG, a company that is looking for success in being different, to start acting like everyone else, and if they did a lot of us would probably start to wonder what the point of buying here is at that point.
ThreeSon: GOG doesn't have any input, one way or the other, regarding the issuing of Steam keys. As JMich pointed out, it's entirely the decision of the developer.
And if developers did start to issue keys, it could only be beneficial to GOG, with no downside for them at all. Right now I have to decide whether to purchase a game I want through GOG or Steam. But if developers issued Steam keys to GOG purchasers, I would
always purchase the game through GOG, because then I would have access to all the benefits instead of just half of them.
I see little to no benefit for GOG and a fairly huge downside. I buy nearly all of my games here, because I'm not giving any money to Valve.
I'm not sure how common that is, but if giving money to GOG results in Valve having more money, it makes it less desirable to shop here.
hedwards: It's not non-zero, where do you think Valve gets the money to pay for bandwidth? It's through the game sales, the other option would be for the developer to pay Valve to provide the service.
In either case, somebody is paying for those Steam keys.
ThreeSon: Valve owns something like 80% of the digital distribution market on PC. You really think they're going to feel the bandwidth impact of a tiny portion of their catalog being downloaded by a tiny fraction of their user base? We're talking about pennies here, assuming it amounts to anything at all.
If GOG had no issue with giving out a complimentary GOG.com download of a 25 GB game like The Witcher 2 to all Steam purchases of the game (kudos for that, GOG team), I can pretty much guarantee that Valve wouldn't incur any financial hardship at all.
Besides, Valve issues the keys for free. If they wanted to charge developers for that service, they could. But they don't. That is a conscious business decision on their part, not a act of charity. They do this to build community goodwill and deflect criticism of their current position in the market. That community goodwill translates into additional dollars for them.
Valve is a business, not a charity. Why should they give away any bandwidth to the competition?