HereForTheBeer: I have to ask: why is it going to cost a lot of money?"
zeroxxx: Providing servers to download them cost them money...
But he said:
The number of XP users nowadays is probably smaller than Linux user base.
So there aren't going to be that many; even if there were, those customers would instead be downloading versions that no longer function under XP - and then pestering Support for help. The number of downloads wouldn't change. The company has told us from the get-go that customers will be able to download their games as often as they want:
https://support.gog.com/hc/en-us/articles/212184749-Can-I-re-download-my-purchased-items-
Can I re-download my purchased items?
Is there a limit to the number of re-downloads? You can always re-download items bought at GOG.com via the “My account” page. Also, there is no limit to the number of redownloads, but please remember that you're not allowed to share your GOG.com account with other users as only you are entitled to download items from your account.
They've essentially positioned themselves as cloud storage for our libraries, and have known all along they'll need to pay for server traffic.
tammerwhisk: They probably don't have anything to actually test or confirm what does or doesn't work on XP at this juncture, and that would still require work on their part.
For me, anyway, I think it's reasonable that gOg don't put more effort effort into those titles. It shouldn't be necessary anyway: the work was done already, and the OS in question isn't changing. Support can say "We no longer offer support for games operating under the following OSes, but you can get the last known-good version of game XYZ here: <link>." At that point further problems are on the customer's side: they got it working well under XP, and the game didn't change and the OS no longer changes, so any problems are most likely caused by something the customer did.
As for storage of the installers, is it really that much? Can anyone with nearly the entire library chime in on how much hard drive space is taken up? 10 TB? I know they'll need multiple copies to handle the potential load but that is mitigated by decreasing the load on Support.
Anyway, I don't see how it's going to cost much to provide access to the last version that is already massaged for XP and is not Galaxy-fied. And they can offset that by saying they are no longer able to provide support for games running under whichever old OS.
If we see a lot of previously-good installers getting messed up for old OSes with the addition of Galaxy-necessary integration (we get it: Galaxy is their future), I'd like to see that they keep the last known-good versions available. It's a customer-friendly move that shouldn't cost much if anything: they would no longer need to develop new solutions for those games under XP, and can drop all but the most basic support for those games under the old OSes.