I agree with Kairon. Anybody can make commercial software for Windows. That's part of the appeal. To change that would effectively change the whole nature of PCs and people like PCs for a reason. If you want a closed system, fine, but MS shouldn't change the nature of a product that a large market of people already like. If I want a Smartphone setup, I'll buy a Smartphone.
It's like if Nintendo decided to start making casual games... oh wait.
Casual games have existed long before the terminology came about. The old arcade and puzzle games like Tetris, Pac-Man, Bomberman, Donkey Kong (arcade), Mario Bros. (arcade), Punch Out, Asteroids, Centipede, Missile Command, Joust, Tecmo Bowl, etc. would be considered "casual games" in today's world. In fact, a large majority of games made in the 1970's and 1980's were "casual games".
Nintendo has been making "casual games" for decades, since before the NES/Famicom era. Also, Nintendo didn't create anything "new" when they made Wii Sports, they simply brought gaming back to its humble roots.