X and SteamOS

One of the reasons why consoles are popular, and why Steam has become a successful tool (on Windows) is because it "just works". Consoles are not general purpose computing devices, Steam is not a platform for distributing arbitrary software.

If you want to write games doing something... unusual... or run those games, feel free. If you want to be very confident an arbitrary game from the store will work, or be very confident your game will have near zero compatibility related support questions, use Steam.

X is designed to do... pretty much anything. Getting to a state of "always works" requires limiting that down. Ethics has nothing to do with it.