Meyniro: Yes, and now 7 is not a modern operating system. It was released 11(!) years ago.
Supporting old games is one thing, but supporting old systems is another.
MFED: Windows 7 NOT modern anymore? What is wrong suddenly with the Windows 7 Dekstop (look&feel)? And "
spyware Windows 10" ist for you a solution? I think you tend to exaggerate!
I think that it's a little hard to argue that an OS is modern when it's almost 11 years old. You can argue that it's still solid and worth using and that the newer OSes aren't actually better, but it's hard to argue that it's modern.
Regardless, if Microsoft had continued to provide driver and security updates to Windows 7, then it would have been fine to use it and might even have been perfectly reasonable to expect major software to support it. However, Microsoft has ended support, which makes it an ever increasing security risk to run it if you're connected to the internet. So, while Windows 10 definitely has problems, it's increasingly foolish to run Windows 7 on any machine connected to the internet - just like you shouldn't be running XP or Vista on any machine connected to the internet (though obviously, in their cases, the situation is that much worse, because they've gone longer without security updates). Anyone who wishes to continue to run Windows 7 in spite of the risks is free to do so, and it makes perfect sense to be pissed at Microsoft over what they've done with Windows 10, but it's unreasonable to expect companies to support programs running on Windows 7 when Microsoft isn't supporting it anymore.
And on top of all of the security risks, there are solid development reasons for not wanting to support such an old operating system. There are APIs and frameworks which exist and are supported for Windows 10 but which not only aren't supported on Windows 7 but have actually never existed for Windows 7. And of course, anyone supporting an application on Windows 7 is going to have to spend time and money testing on Windows 7 and fixing issues specific to it. So, from a development standpoint, it really doesn't make much sense at this point to support Windows 7 (especially for a smaller outfit like GoG).
Personally, I wish that Windows 10 did not have the spyware that it does, and that's one reason why I do not run it as my primary OS, but given the security risks involved, running Windows 7 is only going to become more and more foolish over time unless you avoid connecting it to the internet. Ultimately, anyone using Windows 7 is going to need to either switch to Windows 10 or stop using Windows if they don't want to run a high risk of getting infected by some kind of virus or other malware. It's a frustrating situation to say the least, but unfortunately, that's just the way that it is.