I don't really like fragmenting my library across multiple services, so I used to mostly only buy old games and reboots of old games on GOG, so there'd at least be a logical categorization between my Steam games and my GOG games.  I see this new feature as a way to try to counter that inertia Steam has with OCD people like me.

Now that I know that I'll be able to consolidate more of my library on GOG over time, I think I'm going to start favoring them for new games, too.  I hope it has a similar effect on other people; I always felt bad I wasn't supporting GOG -- and, by extension, their consumer-friendly business practices -- more, just for a little extra convenience.