GOG is being mentioned because it isn't DRM (for those of us who want our games to be completely DRM-free), and for many and like Steam, you can also have "most of your games in one place".
It's just preference.
I liked that the Broken Sword Kickstarter has GoG.com as a distribution platform. It would be great if Obsidian would also consider it as a choice of distribution platform when the game is released.