ET3D: I know not everyone feels this way, but this, coupled with my belief (based on experience) that games I bought don't just go and disappear one day without warning, contributes to my lack of backing up.
The Desura case gives some perspective to this. It seemed to come as a surprise to most if not all, and then each and every had to make up their mind if they want to try to download some or all of their games from Desura as long as the servers are online, or just let them go. Naturally, is someone has most of the games on some other service as well, they probably didn't care much. Fortunately I had no games there at all.
For me the reasons to keep local backups of my digital (DRM-free) games:
- If I suddenly get an urge to try some game, it is easier and faster to me to install it from that external HDD, than downloading even several gigabytes of data over my 10Mbit/s cable modem, and then install that. This depends much also on the size of the game I want to try, e.g. if it is less than 100MB, I might just as well re-download the installer from GOG, at least if I am already logged into the GOG website.
- Since I do my gaming on laptops, sometimes I may be longer periods of time somewhere where I don't have a fast or unlimited internet-connection, and still occasionally might want to try out some new game.
- If the unthinkable happened and GOG would go the way of Desura, or EA would buy out GOG and integrate it with EA Origin :), I wouldn't have to rush to download them at that point with the rest of GOG users.
- I also have DRM-free games from some other stores I don't visit anymore at all, and have probably even forgotten about my login details. Like GamersGate, DotEmu, Frictional Games store, Strategy First store etc. I have the games I've bought from those places on the same external HDD as my GOG games, and I couldn't care less even if those stores ceased to exist.
As a matter of fact, I think I am not even eligible anymore to re-download the games from Strategy First. I think they had some sort of limitation how long, or for how many times, you can download your DRM-free game installers from them. Plus, their download system was a true pain in the ass, and slow too. Oh well, I have their games already in my possession, so...
I personally don't see anything odd in keeping a local repository of my DRM-free games, anymore than keeping my old retail PC and console games, or my DVD movies. In fact, keeping the GOG game installers in an external HDD is much less hassle than all those old retail games on those big storage boxes I have at my home.
With my Android games (from Humble Bundle), I feel even a bigger need to keep the apk installers on some sort of USB thumbstick or something, as I have the tablet quite often in places with no or slow (mobile) internet, and the tablet has relatively small storage so you can't have that many games installed at the same time anyway. So if you want to install some new Android game, you might have to uninstall some other games first to make room on the device, and then later you might want to install them back after all.