We all know how annoying it is that we can't have all our favourite games on GOG with the snap of our fingers but we're not the only ones. Sony have the same problems with their PSOne classics range

Licenses can cause all kinds of problems and even if every publisher joins GOG there will be games they can never release because of license issues. It sucks.

It's a reason to keep DRM-free backups of every game released, since some day there will be no other way to play them.