Besides the fact that all the divinity series and Dragon Commander are already on Gog.com, as a Kickstarter backer, I was surprised to see Larian hasn't given the GoG option to the other people. Since it's unlikely for them to keep the GoG option exclusive to the backers, I presume GoG purchase will get available to the public sooner or later. However, even it wouldn't let all the non-backers happy due to some pre-purchase goodies. This feels kind of odd since it must be good for Gog to build the image of supporting indie companies, too. Rather, it wouldn't have surprised me if they had announced Gog release of Divinity at the live streaming along with the Witcher promotion.
The problem is Larian doesn't understand why Steam annoys people that doesn't want to deal with DRM at all, even if it's "just" required to install the game, and re required to install every update they will release. (Seems like none tough it will be a big mess to tell DRM-free and go the steam route). I was surprised too as there were no mention of obligatory platform when i pre ordered, and i never had to deal with Steam on other Larian's games. It feels odd to me too, didn't had the money at the time of the backing, pre ordered as soon as it was possible for me and got told by a friend they will force Steam to install the game on physical boxes. That's just free punishing of fan, that's how it feels, that's odd, usually the game punish you if you don't play correctly, not the guys behind the game for buying the game.