That's basically what an AppleTV box does. However, you still have to pay (and search) a large number of services to find what you want, and there's no guarantee that it will be ad-free no matter how much you pay. The way these people think, the more you're willing to pay to avoid ads, the more your eyeballs are worth.

As Gabe Newell put it, piracy isn't a legal problem or a revenue problem, it's a customer-service problem. Serve the customer, or someone else will.