For the longest time, Microsoft was writing into its OEM contracts that they had to pay per machine shipped, regardless of if Windows was actually installed. It's well-documented, including by Wikipedia[1]. As for why they stopped, it certainly wasn't out of a sense of kindness or duty. My best guess is that it was an indirect result of the antitrust lawsuits[2], and they figured that they didn't want any more legal attention.

[1] "Microsoft once assessed license fees based on the number of computers an OEM sold, regardless of whether a Windows license was included." https://en.wikipedia.org/wiki/Bundling_of_Microsoft_Windows [2] The case in question concerned software bundling of Internet Explorer, but it's not hard to imagine eventual attention towards OS bundling of Windows itself. https://en.wikipedia.org/wiki/United_States_v._Microsoft_Cor....

Because there's no way Microsoft is charging Lenovo $140 for Windows Home, and also because people who don't want Windows are likely less price sensitive than the average user so you can charge them more anyway.

Microsoft was making it very hard for OEMs to sell some computers without Windows for a number of decades. I would assume they are more afraid of an increase in law enforcement than usual.

I'm not suprised, but still happy.