To each - his own, as the ancient Romans said. If you love Windows 10 so much, that's your right. But NO ONE GIVEN you the right to decide for others.
The developers of "Necromunda: Hired Gun" implemented support for Windows 7 - they got my money. The developers of "The Riftbreaker" preferred "modern OS" - they didn't get my money. You want to support them with your wallet - go ahead.
And Windows 7 is at this point the OS Caesar had on his PDA and other ancient relics. Only reason the Library of Alexandria burned is because the fire control system was still running Windows XP, and not even SP2.
Seriously though, if a developer won't add support for a decade old OS, which has a completely different core, then it's simply a matter of not playing that game. No need to hate on the developer for that. Upgrade your OS instead, you can get Windows 10 for free with a genuine Windows 7 lisence.
Or you can dual-boot, just clone your Windows 7 to a different drive for less hassle down the line, and upgrade one of them to Win 10, and keep using both on the same machine. A 250 GB SSD, which is all you need for a standalone Windows 10 install, cost peanuts.
If anything, hate on Microsoft for making a new OS instead of making the previous one 100 %. Personally, Windows 7 has a lot of benefits I would like to see in Windows 10 - like no freakin' nagging(!) when setting a machine up for the first time. And less spyware. And a way better control panel instead of the Win 10 app crap.
But it is what it is. Adapt by using a modern OS or stay away from games with "limited OS support".