Nirth: I think some marketing to promote GOG users to back up the installers would be far more effective and worth GOG's resources.
timppu: But first GOG should implement a "Download all your games+extras at once"-button into their client.
Which I feel they are not willing to do, because that might make the the burden on their download servers shoot through the roof, as lots of people would try to backup their vast GOG collection, even many times when many games in their collection have received updates. I presume GOG wants people mostly just download individual games they are going to play right there (not e.g. download all their games over and over again once a month or so), just to keep the burden on servers at a moderate level. And keep local backups of those individual games so that they don't unnecessarily download them several times.
I've been wanting a similar "Download all" button also in the Steam client, but it seems to be missing there too, probably for similar reasons. Plus, the Steam client seems to choke easily if I try to download lots of games at the same time, it becomes very unresponsive and it becomes near impossible to start more downloads.
Well, if they coded it properly, then it could download things once and then just download updates later on or things that get corrupted.
Also, I think that most people would be using it to begin with and so it would just be a small number of games at a time. It's a relatively small group that have more than 100 games and few have more than 300.