Ravenvolf: You do realise that gog and Steam are competitors right? Why would one give away the product of another? It makes no sense.
Snaddre: Do you mean no sense for steam or for gog? Gog has already made the money on the sale of the game. Generating a Steam key through steamworks is free for the developers and online stores who have an agreement with Valve, such as humble. Then users are free to use the Steam platform for patching, community, and so on. Why would Steam do this for free? Because the Steam store is also a part of the platform. This means that when I want to play Banished on Steam to use the community, achievements etc, I also got simple access to their store.
So it makes total sense, from a business perspective. Gog is the first store I've encountered that does not generate keys. Another example is Amazon.
Again, products are not given away. You pay for it once, and unlock it on two separate platforms. Same IP, different platforms.
It makes sense for the developer to give away keys. But It makes no sense for either gog or Steam, they are competing stores. The developer giving away keys is a separate matter. Gog or Steam is not the developer.
You also don't get a DRM free copy if you buy it from Steam.
If the developer wan't to give away a steam key for everyone who bought in on gog, good on them.
I got a Steam key for Inquisitor, which I bought here on gog, because the developer gave away the key if you email them proof that you own it on gog (they accepted a receipt or screenshot of the game on your shelf). Under no circumstances did I expect gog to give away the keys because it has nothing to do with them.
If you have a problem with not having a Steam key, contact the developer, it has nothing to do with Gog or Steam. Hopefully the developer will help you out, but I wouldn't expect it, it would be very nice of them. I suggest contacting him very politely and not demanding a key. Good luck.