At the end of the day though, most people don't buy games solely to help developers. They are buying games because they want to play games. Rewarding developers is a nice side effect and all, and it's great that it's helping them to make a living, but we don't go into supermarkets and buy vegetables to help farmers, we buy vegetables because we want to eat. Gamers should not be in the business of having to justify a developer's existence.
That being said, DRM-free distribution of games is still very nascent, and it's a development that is absolutely necessary. If it doesn't take hold, PC gaming will gradually move more and more towards a rental model, which will inevitably eventually result in it dying out. For better or worse, GOG is pretty much the public figurehead of this change, and if it fails, it reflects very badly on DRM-freedom as a whole.
In this respect, gamers have a vested interest in ensuring that GOG goes about its business properly. If it failed due to some factor that isn't even related to DRM, it really would be a great shame.