My understanding is that while Scott Guthrie & Co is influential today, there is at least one camp of people that opposes this new openness. There is no guarantee the "other camp" won't get influential in the future or sabotage what they can.

Even dot net core is not free and open source yet.

https://github.com/dotnet/source-build/blob/release/3.0/Docu...

Even as they say everything is fine, I imagine they are fending off constant attacks from within Microsoft.