I recently contacted a developer/publisher about bringing their games here and they said: "We'd be on their service if they could match everyone's standard 70/30 rev share."
Perhaps they revealed more than they should have but it did open my eyes to an issue I hadn't really considered. ...
Surely we as a customer/gamer community would like to have more and cheaper games on GOG. I am all for it, even if both is probably not achievable at the same time.
My guess is that the DRM free, worldwide same price stance is also (maybe even more) limiting the availability. Take 2 is known for notoriously relying on DRM. They woudn't come here for any revenue sharing, would they?
Also quality matters. Maybe we don't every game here. GamersGate does this policy and 80% of the games on GamersGate are quite bad games.
In the end the details are probably only GOG's business. We can only urge them to bring more games here.
I would advice GOG to not stay too far from the average of the industry, whatever it is. It probably means that there is some wisdom in it, even if 70/30 sounds pretty artificial and not very flexible.
Maybe they can increase the share of the developer if much games are sold, this way successful games are also highly profitable to have on GOG, and who is not convinced that his/her game will be highly successful. :)
60/40 for the first 10000 units
70/30 for the next 50000 units
80/20 for all above