Because many of those systems would have been put together in the lead up to release too, and aren't going to be replaced any time soon; that one time cost will have just been paid in full for new systems and the lack of easy access to transistioning to the new OS will prevent the lighting up of functionality around that hardware. It's questionable to me if Windows 10 gets direct storage now or if that becomes a Windows 11 exclusive feature, for instance. If I just spent 2k on a system only to find that there was no upgrade path to get full use out of my nvme drives I'd be annoyed. Especially since that restriction would be transparently artificial and clearly unnecessary.How would not allowing upgrades screw them over ? Windows is a one time cost . Windows 10 is going to be 6 years old in July. $100-200 for an optional purchase is not the end of the world
If it has a cost at all, it better be like the historical way this has been handled, with cheaper upgrade licenses and a clear method for in place upgrades. There's absolutely no benefit to making it harder for people on older systems that are still good enough that they aren't going to hold features back from moving to the most recent version of the OS. Anything else can get covered by a change to min spec.