Because console and PC gaming have entirely different origins. Consoles are rooted in arcade machines, pinball and carnival toys, and originally sold as being able to play your favourite arcade games at home. This is why the most prominent console makers are toymakers, like the late Gunpei Yokoi, or Nolan Bushnell using his summer work experience at a carnival when designing the original Atari or SEGA originally being vending machine and later arcade makers. PCs are rooted as... computing machines, originally made for computing and managing documents, with the games being something on the aside. That's why the most prominent PC game makers like Sid Meier, Richard Garriott and John Carmack are obsessed by numbers and their games are inspired by elaborate tabletop games.
Buying and mantaining a console is like buying a complete action figure, where you have to pay up for new weapons and armours, while PC is like buying a construction kit that you also need to paint yourself. It's not about as control as much as console manufacturers paying respect to their origins. I, for one, don't support this intermingling ot console and PC gaming that you're trying to invoke! If anything, consoles having a OS at all is denying the 'plug-in-and-play' console origins! At least having paid themes is trying to strike a compromise. It's a complete package because the OS is still completely functional and does everything it's intended to do.