Minecraft is a bad argument. Getting rid of the other versions would have been bad publicity, and when it's already on other platforms, releasing it for some more shouldn't hurt. Exclusivity is already lost, so there's only profit to be made by releasing the game on other platforms. It wouldn't have benefited MS to not release it elsewhere.
As for PC, it's Microsoft's platform for gaming purposes. Most PC gaming happens on Windows, and in the current situation, I'm sure MS will do whatever it can to strengthen the position of Windows. That said, MS's efforts to bring games to PC have still been relatively weak.
Also, you're cherry picking cases to try to prove your argument. In the grand scale of things, MS shares very little.







