MS is a Wolf in Sheeps clothing
when it comes to FOSS. They love it that they can get their sticky mits on lots of stuff for free. No need to pay devs top dollar/yen/euro when there are thousands of devs out there doing it for free.
Then they'll cherry pick some of the best apps and suddenly release their own app that is closed source and .... you know the rest. $$$$$ of income on a monthly basis. The devs working for free have zero chance of winning a lawsuit against the Redmond behemoth.