jakandratchet: pulling games from libraries like this should be illegal. The licence agreements shouldn't be allowed to work like this.
hedwards: AFAIK, they only go to that length when there wasn't a license to allow the sale in the first place and they did provide compensation for the removals.
Generally speaking though, the licenses include language to allow GOG to continue to distribute previously sold copies to the buyer after the license expires. The license itself just covers the selling of new licensed copies, not the older ones.
Occasionally, you have things like with Quake where they yank the original version due to the soundtrack not technically being licensed and replace it with an authorized version, but in that case, if you downloaded the game immediately, like I did, you can still use the older version, it might just require some effort to keep up with potential patching issues later on.
You can also patch back in the music via other sites. Though imo companies should try to get lifetime rights to such to avoid this kind of thing.
GameRager: If one has a small HDD and a large library this is sadly just a pipe dream(even if one streamlines installers to remove unneeded stuff). :(
Maighstir: External 6TB HDDs on Amazon (UK) start at about £110. 8TB ones start at £135.
My library is currently at 4.1TB with a bit over 1100 games, giving an average of almost 4 GB per game - and that includes copies in all available languages and for all systems in the cases where that's applicable. Provided you only download the installers for one or two languages and one system, that should shrink a bit (I haven't bothered to check how much), and a 6TB HDD should suffice for a while, even when accounting for the fact that it's probably 5TB usable.
I have a laptop without the ability to change HDDs(afaik)...also even if I could I wouldn't want to risk data loss/corruption by cloning the data to another drive/etc. Also extrenal drives are sometimes cr*p for newer games.