I think it was more of a slow transition and more focused on Linux. Once Linux become big enough to disrupt them that’s when they started to change . Microsoft research has been contributing to Haskell for a long time. I think they are moving forward a more service oriented company that doesn’t care what you do but will make it easier to stay in their ecosystem like Azure or just focus on getting more developer goodwill and lock-in .

They saw that developers are eager enough to do Microsoft's work for free. See .NET Core and its related projects where Microsoft accepts a lot of patches from outside contributors and sometimes needs to admit that others know their code and its sometimes decade old history better than they do.

I think the greater community would rather have it this way. Trying to get a bug in .Net 1.x fixed was not a pleasant or completely legal experience (peaking into .net assemblies, and decompiling to even get the to root of the issue).

Even if I only ever had to do it once... having the option is much better than not.